Set the maximum character length of a UITextField

Question

How can I set the maximum amount of characters in a UITextField on the iPhone SDK when I load up a UIView

User · Answer

I have implemented a UITextField Extension to add a maxLength property to it.

It's based on Xcode 6 IBInspectables, so you can set the maxLength limit on the Interface builder.

Here is the implementation:

UITextField+MaxLength.h

#import <UIKit/UIKit.h>

@interface UITextField_MaxLength : UITextField<UITextFieldDelegate>

@property (nonatomic)IBInspectable int textMaxLength;
@end

UITextField+MaxLength.m

#import "UITextField+MaxLength.h"

@interface UITextField_MaxLength()

@property (nonatomic, assign) id <UITextFieldDelegate> superDelegate;

@end

@implementation UITextField_MaxLength

- (BOOL)textField:(UITextField *) textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {

    //validate the length, only if it's set to a non zero value
    if (self.textMaxLength>0) {
        if(range.length + range.location > textField.text.length)
            return NO;

        if (textField.text.length+string.length - range.length>self.textMaxLength) {
            return NO;
        }
    }

    //if length validation was passed, query the super class to see if the delegate method is implemented there
    if (self.superDelegate && [self.superDelegate respondsToSelector:@selector(textField:shouldChangeCharactersInRange:replacementString:)]) {
        return [self.superDelegate textField:textField shouldChangeCharactersInRange:range replacementString:string];
    }
    else{
        //if the super class does not implement the delegate method, simply return YES as the length validation was passed
        return YES;
    }
}

- (void)setDelegate:(id<UITextFieldDelegate>)delegate {
    if (delegate == self)
        return;
    self.superDelegate = delegate;
    [super setDelegate:self];
}

//forward all non overriden delegate methods
- (id)forwardingTargetForSelector:(SEL)aSelector {
    if ([self.superDelegate  respondsToSelector:aSelector])
        return self.superDelegate;

    return [super forwardingTargetForSelector:aSelector];
}

- (BOOL)respondsToSelector:(SEL)aSelector {
    if ([self.superDelegate respondsToSelector:aSelector])
        return YES;

    return [super respondsToSelector:aSelector];
}
@end

User · Answer

Slightly beyond answering the original question  and expanding on Frouo s answer  here are extensions to trim a String of whitespace and to a max length  and to utilize those String extensions to trim a UITextField to a max length      In String Extensions swift  extension String      func trimmedString   - gt  String       var trimmedString   self stringByTrimmingCharactersInSet NSCharacterSet whitespaceAndNewlineCharacterSet        let components   trimmedString componentsSeparatedByCharactersInSet NSCharacterSet whitespaceAndNewlineCharacterSet    filter   count  0   gt  0       return     join components         func trimmedStringToMaxLength maxLength  Int  - gt  String       return trimmedString   substringToIndex advance startIndex  min count self   maxLength    trimmedString              In UITextField Extensions swift  private var maxLengthDictionary    UITextField   Int    private var textFieldMaxLength   20  extension UITextField       IBInspectable var maxLength  Int       get         if let maxLength   maxLengthDictionary self            return maxLength         else           return textFieldMaxLength                   set         maxLengthDictionary self    newValue  lt  textFieldMaxLength   1   newValue   textFieldMaxLength              func trimAndLimitToMaxLength         text   text trimmedStringToMaxLength maxLength          let someTextField   UITextField   let someString       This   is   a   string   that   is longer than allowable for a text field      someTextField text   someString someTextField trimAndLimitToMaxLength   println someTextField text     Prints  This is a string tha  let anotherTextField   UITextField   anotherTextField maxLength   5 anotherTextField text   someString anotherTextField trimAndLimitToMaxLength   println anotherTextField text     Prints  This    trimAndLimitToMaxLength   could be used in UITextFieldDelegate s textFieldDidEndEditing     so that a user could enter or paste in a longer than acceptable string and then shorten it vs  just cutting off the input at the max length  In doing this  I would also set attributed text styles to indicate any portion of the text that goes beyond the acceptable length  e g    NSBackgroundColorAttributeName   UIColor redColor    NSForegroundColorAttributeName   UIColor whiteColor    NSStrikethroughStyleAttributeName   NSNumber int  1

User · Answer

You can t do this directly - UITextField has no maxLength attribute  but you can set the UITextField s delegate  then use   -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string

User · Answer

I have implemented a UITextField Extension to add a maxLength property to it.

It's based on Xcode 6 IBInspectables, so you can set the maxLength limit on the Interface builder.

Here is the implementation:

UITextField+MaxLength.h

#import <UIKit/UIKit.h>

@interface UITextField_MaxLength : UITextField<UITextFieldDelegate>

@property (nonatomic)IBInspectable int textMaxLength;
@end

UITextField+MaxLength.m

#import "UITextField+MaxLength.h"

@interface UITextField_MaxLength()

@property (nonatomic, assign) id <UITextFieldDelegate> superDelegate;

@end

@implementation UITextField_MaxLength

- (BOOL)textField:(UITextField *) textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {

    //validate the length, only if it's set to a non zero value
    if (self.textMaxLength>0) {
        if(range.length + range.location > textField.text.length)
            return NO;

        if (textField.text.length+string.length - range.length>self.textMaxLength) {
            return NO;
        }
    }

    //if length validation was passed, query the super class to see if the delegate method is implemented there
    if (self.superDelegate && [self.superDelegate respondsToSelector:@selector(textField:shouldChangeCharactersInRange:replacementString:)]) {
        return [self.superDelegate textField:textField shouldChangeCharactersInRange:range replacementString:string];
    }
    else{
        //if the super class does not implement the delegate method, simply return YES as the length validation was passed
        return YES;
    }
}

- (void)setDelegate:(id<UITextFieldDelegate>)delegate {
    if (delegate == self)
        return;
    self.superDelegate = delegate;
    [super setDelegate:self];
}

//forward all non overriden delegate methods
- (id)forwardingTargetForSelector:(SEL)aSelector {
    if ([self.superDelegate  respondsToSelector:aSelector])
        return self.superDelegate;

    return [super forwardingTargetForSelector:aSelector];
}

- (BOOL)respondsToSelector:(SEL)aSelector {
    if ([self.superDelegate respondsToSelector:aSelector])
        return YES;

    return [super respondsToSelector:aSelector];
}
@end

User · Answer

The best way would be to set up a notification on the text changing  In your -awakeFromNib of your view controller method you ll want     NSNotificationCenter defaultCenter  addObserver self selector  selector limitTextField   name   UITextFieldTextDidChangeNotification  object myTextField     Then in the same class add   -  void limitTextField  NSNotification   note       int limit   20      if    myTextField stringValue  length   gt  limit             myTextField setStringValue   myTextField stringValue  substringToIndex limit              Then link up the outlet myTextField to your UITextField and it will not let you add any more characters after you hit the limit  Be sure to add this to your dealloc method     NSNotificationCenter defaultCenter  removeObserver self name   UITextFieldTextDidChangeNotification  object myTextField

User · Answer

This should be enough to solve the problem  replace 4 by the limit u want   Just make sure to add delegate in IB   -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string        NSString  newString    textField text stringByReplacingCharactersInRange range withString string        return  newString length lt  4

User · Answer

You can t do this directly - UITextField has no maxLength attribute  but you can set the UITextField s delegate  then use   -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string

User · Answer

The following code is similar to sickp s answer but handles correctly copy-paste operations  If you try to paste a text that is longer than the limit  the following code will truncate the text to fit the limit instead of refusing the paste operation completely   -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string       static const NSUInteger limit   70     we limit to 70 characters     NSUInteger allowedLength   limit -  textField text length    range length      if  string length  gt  allowedLength            if  string length  gt  1                   get at least the part of the new string that fits             NSString  limitedString    string substringToIndex allowedLength               NSMutableString  newString    textField text mutableCopy                newString replaceCharactersInRange range withString limitedString               textField text   newString                    return NO        else           return YES

User · Answer

- BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string       if  textField text length  gt   50            return NO            return YES

User · Answer

I want to add to the answer given by  sickp   There is an issue in his Swift code that occurs with any multibyte text  e g  emojis   NSRange and String in Swift are not compatible  so it s frustrating that the delegate class combines them  The trick is simply to convert the String objects to NSString The correct solution  based on what  sickp wrote  is actually this   func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool        let currentText    textField text as NSString      NSString       let currentCharacterCount   currentText length     if range length   range location  gt  currentCharacterCount           return false           let newLength   currentText replacingCharacters in  range  with  string  characters count     return newLength  lt   25

User · Answer

- BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string       if  textField text length  gt   50            return NO            return YES

User · Answer

swift 3 0 This code is working fine when you are paste string more than your character limits  func textView   textView  UITextView  shouldChangeTextIn range  NSRange  replacementText text  String  - gt  Bool           let str    textView text   text          if str characters count  lt   10               return true                   textView text   str substring to  str index str startIndex  offsetBy  10           return false        Thanks for your votes

User · Answer

You can also do this using NotificationCenter in Swift 4    NotificationCenter default addObserver self  selector   selector self handleTextChange recognizer     name  NSNotification Name UITextFieldTextDidChange  object  yourTextField        objc func handleTextChange recognizer  NSNotification                  max length is 50 charater max             let textField   recognizer object as  UITextField              if  textField text  count    gt  50                    let newString  String     textField text as NSString    substring to  50                  textField text   newString

User · Answer

BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string       NSString  newString    textField text stringByReplacingCharactersInRange range withString string        if   txt name text length  gt 100                return NO             return YES

User · Answer

If your purpose of limiting text count is to ensure that text will fit into a UILabel elsewhere  I d avoid using character count  It breaks down with some emoji  trying to truncate a double size emoji will likely crash your app   It s also an issue with some languages like Japanese and Chinese  which have a two-step input process where a simple count just won t work    I built out a UITextField drop-in subclass  MPC CharacterLimitedTextField on github   You feed it the expected output label width and it will handle all languages  emoji  and pasting issues  It will harvest only as many full characters that will fit into the label  regardless of the character count  There s a demo in the project so you can test it to see if it s what you need  Hope it will help anybody who was having the same problems with output length that I was

User · Answer

The best way would be to set up a notification on the text changing  In your -awakeFromNib of your view controller method you ll want     NSNotificationCenter defaultCenter  addObserver self selector  selector limitTextField   name   UITextFieldTextDidChangeNotification  object myTextField     Then in the same class add   -  void limitTextField  NSNotification   note       int limit   20      if    myTextField stringValue  length   gt  limit             myTextField setStringValue   myTextField stringValue  substringToIndex limit              Then link up the outlet myTextField to your UITextField and it will not let you add any more characters after you hit the limit  Be sure to add this to your dealloc method     NSNotificationCenter defaultCenter  removeObserver self name   UITextFieldTextDidChangeNotification  object myTextField

User · Answer

What about this simple approach  Its working fine for me   extension UITextField        func  charactersLimit to Int             if  self text  count  gt  to                self deleteBackward                       Then   someTextField charactersLimit to 16

User · Answer

I did this in Swift for an 8 character limit when using a number pad   func textField textField  UITextField  shouldChangeCharactersInRange range  NSRange  replacementString string  String  - gt  Bool       return   textField text  characters count    MAX LENGTH  amp  amp  string            I had to test for string       to allow the delete button to work on the number pad  otherwise it wouldn t allow deleting characters in the text field after it reached its max

User · Answer

Thank you august   Post   This is the code that I ended up with which works    define MAX LENGTH 20  -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string       if  textField text length  gt   MAX LENGTH  amp  amp  range length    0                return NO     return NO to not change text           else      return YES

User · Answer

For Swift 2 1   func textField textField  UITextField  shouldChangeCharactersInRange range  NSRange  replacementString string  String  - gt  Bool        if  range length   range location  gt  textField text  characters count                 return false             let newLength   textField text  characters count   string characters count - range length     return newLength  lt   25     Hope it helps

User · Answer

This is the correct way to handle max length on UITextField  it allows the return key to exit the resign the textfield as first responder and lets the user backspace when they reach the limit  -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string   int MAX LENGHT   5      if  string isEqualToString    n                   textField resignFirstResponder           return FALSE            else if textField text length  gt  MAX LENGHT-1                if  string isEqualToString       amp  amp  range length    1                        return TRUE                    else                       return FALSE                      else               return TRUE

User · Answer

There is generic solution for setting max length in Swift  By IBInspectable you can add new Attribute in Xcode Attribute Inspector   import UIKit private var maxLengths    UITextField  Int    extension UITextField         IBInspectable var maxLength  Int           get               guard let length   maxLengths self              else                   return Int max                           return length                   set               maxLengths self    newValue             addTarget                  self                  action  Selector  limitLength                     forControlEvents  UIControlEvents EditingChanged                                    func limitLength textField  UITextField            guard let prospectiveText   textField text             where prospectiveText characters count  gt  maxLength else                   return                   let selection   selectedTextRange         text   prospectiveText substringWithRange              Range lt String Index gt  prospectiveText startIndex    lt  prospectiveText startIndex advancedBy maxLength                     selectedTextRange   selection

User · Answer

we can set the range of textfield like this    - BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range  replacementString  NSString   string        int setrange   20       return    textField text length  gt setrange  amp  amp   string length   gt  range length

User · Answer

For Xamarin   YourTextField ShouldChangeCharacters    delegate UITextField textField  NSRange range  string replacementString                        return  range Location   replacementString Length   lt   4     MaxLength    4

User · Answer

Often you have multiple input fields with a different length   -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string       int allowedLength      switch textField tag            case 1               allowedLength   MAXLENGTHNAME          triggered for input fields with tag   1             break          case 2              allowedLength   MAXLENGTHADDRESS       triggered for input fields with tag   2             break          default              allowedLength   MAXLENGTHDEFAULT       length default when no tag   0  value  255             break             if  textField text length  gt   allowedLength  amp  amp  range length    0            return NO     Change not allowed       else           return YES     Change allowed

User · Answer

Swift 4 2 and UITextFieldDelegate method  This works for me and limits the textfield to have a max input of 8 characters  Hopefully NSRange will eventually be changed to Range but for now I am happy to use NSString as creating a Range from NSRange involves dealing with another optional   func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool       let text   textField text           let nsString   text as NSString     let newText   nsString replacingCharacters in  range  with  string      return newText count  lt   8

User · Answer

I found this quick and simple  -  IBAction backgroundClick  id sender       if  mytext length  lt   7             mytext resignFirstResponder         else           UIAlertView  alert     UIAlertView alloc  initWithTitle   Too Big                                                           message   Please Shorten Name                                                         delegate nil                                                cancelButtonTitle   Cancel                                                otherButtonTitles nil            alert show            alert release

User · Answer

To complete August answer  an possible implementation of the proposed function   see UITextField s delegate    I did not test domness code  but mine do not get stuck if the user reached the limit  and it is compatible with a new string that comes replace a smaller or equal one   - BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string         limit the size       int limit   20      return    textField text length  gt limit  amp  amp   string length   gt  range length

User · Answer

I did this in Swift for an 8 character limit when using a number pad   func textField textField  UITextField  shouldChangeCharactersInRange range  NSRange  replacementString string  String  - gt  Bool       return   textField text  characters count    MAX LENGTH  amp  amp  string            I had to test for string       to allow the delete button to work on the number pad  otherwise it wouldn t allow deleting characters in the text field after it reached its max

User · Answer

I give a supplementary answer based on  Frouo   I think his answer is the most beautiful way  Becuase it s a common control we can reuse    private var kAssociationKeyMaxLength  Int   0  extension UITextField         IBInspectable var maxLength  Int           get               if let length   objc getAssociatedObject self   amp kAssociationKeyMaxLength  as  Int                   return length               else                   return Int max                                 set               objc setAssociatedObject self   amp kAssociationKeyMaxLength  newValue   OBJC ASSOCIATION RETAIN              self addTarget self  action   selector checkMaxLength   for   editingChanged                       func checkMaxLength textField  UITextField             guard  self isInputMethod    let prospectiveText   self text              prospectiveText count  gt  maxLength             else                   return                    let selection   selectedTextRange         let maxCharIndex   prospectiveText index prospectiveText startIndex  offsetBy  maxLength          text   prospectiveText substring to  maxCharIndex          selectedTextRange   selection              The method is used to cancel the check when use Chinese Pinyin input method        Becuase the alphabet also appears in the textfield when inputting  we should cancel the check      func isInputMethod   - gt  Bool           if let positionRange   self markedTextRange               if let     self position from  positionRange start  offset  0                    return true                                 return false

User · Answer

Use below extension to set the maximum character length of a UITextField and UITextView   Swift 4 0      private var kAssociationKeyMaxLength  Int   0     private var kAssociationKeyMaxLengthTextView  Int   0     extension UITextField              IBInspectable var maxLength  Int               get                   if let length   objc getAssociatedObject self   amp kAssociationKeyMaxLength  as  Int                       return length                   else                       return Int max                                             set                   objc setAssociatedObject self   amp kAssociationKeyMaxLength  newValue   OBJC ASSOCIATION RETAIN                  addTarget self  action   selector checkMaxLength   for   editingChanged                                    objc func checkMaxLength textField  UITextField                guard let prospectiveText   self text                  prospectiveText count  gt  maxLength                 else                       return                            let selection   selectedTextRange              let indexEndOfText   prospectiveText index prospectiveText startIndex  offsetBy  maxLength              let substring   prospectiveText    lt indexEndOfText              text   String substring               selectedTextRange   selection                   UITextView  extension UITextView UITextViewDelegate              IBInspectable var maxLength  Int               get                   if let length   objc getAssociatedObject self   amp kAssociationKeyMaxLengthTextView  as  Int                       return length                   else                       return Int max                                             set                   self delegate   self                  objc setAssociatedObject self   amp kAssociationKeyMaxLengthTextView  newValue   OBJC ASSOCIATION RETAIN                                   public func textViewDidChange   textView  UITextView                checkMaxLength textField  self                     objc func checkMaxLength textField  UITextView                guard let prospectiveText   self text                  prospectiveText count  gt  maxLength                 else                       return                            let selection   selectedTextRange              let indexEndOfText   prospectiveText index prospectiveText startIndex  offsetBy  maxLength              let substring   prospectiveText    lt indexEndOfText              text   String substring               selectedTextRange   selection                   You can set limit below

User · Answer

Swift 4 2   By implementing UITextFieldDelegate method   ViewController   class MyViewController  UIViewController        let MAX LENGTH   256       IBOutlet weak var myTextField  UITextField       override viewDidLoad             self myTextField delegate   self          Delegate   extension MyViewController  UITextFieldDelegate        func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool           let userText    textView text               var newText              if range length  gt  0               let txt   NSString string  userText              if txt length  gt  0                   newText   txt replacingCharacters in  range  with  text                          else               newText   userText   text                   return newText count  lt   MAX LENGTH

User · Answer

I have open sourced a UITextField subclass  STATextField  that offers this functionality  and much more  with its maxCharacterLength property

User · Answer

To make it work with cut  amp  paste of strings of any length  I would suggest changing the function to something like     define MAX LENGTH 20  -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string               NSInteger insertDelta   string length - range length           if  textField text length   insertDelta  gt  MAX LENGTH                       return NO     the new string would be longer than MAX LENGTH                   else               return YES

User · Answer

The Problem with some of the answer given above is  For example I have a text field and I have to set a limit of 15 characters input  then it stops after entering 15th Character  but they Don t allow to delete  That is the delete button also don t work  As I was facing the same problem  Came out with the solution   Given Below  Works Perfect for Me  -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string    if textField tag  6         if   textField text length  lt  30                return YES               else if      isEqualToString string                 textField text  textField text substringToIndex 30               return NO      else        return YES         I am having a text field  whose tag I have set  6  and I have restricted the max char limit   30   works fine in every case

User · Answer

Swift 3 version         This will NOT work with Swift 2 x           First create a new Swift file   TextFieldMaxLength swift  and then add the code below   import UIKit  private var maxLengths    UITextField  Int     extension UITextField        IBInspectable var maxLength  Int          get              guard let length   maxLengths self                else                   return Int max               return length         set         maxLengths self    newValue       addTarget           self           action   selector limitLength            for  UIControlEvents editingChanged                func limitLength textField  UITextField        guard let prospectiveText   textField text          prospectiveText characters count  gt  maxLength     else           return           let selection   selectedTextRange    let maxCharIndex   prospectiveText index prospectiveText startIndex  offsetBy  maxLength     text   prospectiveText substring to  maxCharIndex     selectedTextRange   selection          and then you will see in Storyboard a new field  Max Length  when you select any TextField  if you still have more questions check out this link  http   www globalnerdy com 2016 05 18 ios-programming-trick-how-to-use-xcode-to-set-a-text-fields-maximum-length-visual-studio-style

User · Answer

I have open sourced a UITextField subclass  STATextField  that offers this functionality  and much more  with its maxCharacterLength property

User · Answer

Use this code here RESTRICTED LENGTH is length you want to restrict for textfield      -  BOOL textField  UITextField   textField     shouldChangeCharactersInRange  NSRange range replacementString  NSString   string       if  textField    nameTF        int limit   RESTRICTED LENGTH - 1      return    textField text length  gt limit  amp  amp   string length   gt  range length            else          return YES        return NO

User · Answer

for Swift 3 1 or later  firstly add protocol UITextFieldDelegate   like -  class PinCodeViewController  UIViewController  UITextFieldDelegate                           after that create your UITextField and set delegate  Complete Exp  -  import UIKit  class PinCodeViewController  UIViewController  UITextFieldDelegate    let pinCodetextField  UITextField         let tf   UITextField       tf placeholder    please enter your pincode      tf font   UIFont systemFont ofSize  15      tf borderStyle   UITextBorderStyle roundedRect     tf autocorrectionType   UITextAutocorrectionType no     tf keyboardType   UIKeyboardType numberPad     tf clearButtonMode   UITextFieldViewMode whileEditing      tf contentVerticalAlignment   UIControlContentVerticalAlignment center  return tf          override func viewDidLoad        super viewDidLoad      view addSubview pinCodetextField        ----- setup your textfield anchor or position where you want to show it-----           after that  pinCodetextField delegate   self    setting the delegate     func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool       return   textField text  characters count    6  amp  amp  string                  this is return the maximum characters in textfield

User · Answer

I created this UITextFieldLimit subclass    Multiple textfields supported Set the text length limit Paste prevention Displays a label of left characters inside the textfield  get hidden when you stop editing  Shake animation when no characters left    Grab the UITextFieldLimit h and UITextFieldLimit m from this GitHub repository   https   github com JonathanGurebo UITextFieldLimit  and begin to test   Mark your storyboard-created UITextField and link it to my subclass using the Identity Inspector     Then you can link it to an IBOutlet and set the limit default is 10      Your ViewController h file should contain   if you wan t to modify the setting  like the limit    import  UITextFieldLimit h           property  weak  nonatomic  IBOutlet UITextFieldLimit  textFieldLimit      lt --Your IBOutlet     Your ViewController m file should  synthesize textFieldLimit     Set the text length limit in your ViewController m file   -  void viewDidLoad        super viewDidLoad      Do any additional setup after loading the view  typically from a nib        textFieldLimit setLimit 25      lt -- and you won t be able to put more than 25 characters in the TextField      Hope the class helps you  Good luck

User · Answer

Swift 4 import UIKit  private var kAssociationKeyMaxLength  Int   0  extension UITextField             IBInspectable var maxLength  Int           get               if let length   objc getAssociatedObject self   amp kAssociationKeyMaxLength  as  Int                   return length               else                   return Int max                                 set               objc setAssociatedObject self   amp kAssociationKeyMaxLength  newValue   OBJC ASSOCIATION RETAIN              addTarget self  action   selector checkMaxLength   for   editingChanged                            objc func checkMaxLength textField  UITextField            guard let prospectiveText   self text              prospectiveText count  gt  maxLength             else                   return                            let selection   selectedTextRange                  let indexEndOfText   prospectiveText index prospectiveText startIndex  offsetBy  maxLength          let substring   prospectiveText    lt indexEndOfText          text   String substring                   selectedTextRange   selection          Edit  memory leak issue fixed

User · Answer

Thank you august   Post   This is the code that I ended up with which works    define MAX LENGTH 20  -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string       if  textField text length  gt   MAX LENGTH  amp  amp  range length    0                return NO     return NO to not change text           else      return YES

User · Answer

Got it down to 1 line of code     Set your text view s delegate to  self  then add the  lt UITextViewDelegate gt  in your  h and the following code in your  m      you can adjust the number  7  to be whatever you want your MAXIMUM number of characters to be    - BOOL textView  UITextView   a shouldChangeTextInRange  NSRange b replacementText  NSString   c       return   a text length c length lt  7   c length lt 1   b length gt  c length  gt 0       This code accounts for typing new characters  deleting characters  selecting characters then typing or deleting  selecting characters and cutting  pasting in general  and selecting characters and pasting   Done       Alternatively  another cool way to write this code with bit-operations would be  - BOOL textView  UITextView   a shouldChangeTextInRange  NSRange b replacementText  NSString   c       return 0   a text length c length lt  7   c length lt 1   b length gt  c length

User · Answer

The Problem with some of the answer given above is  For example I have a text field and I have to set a limit of 15 characters input  then it stops after entering 15th Character  but they Don t allow to delete  That is the delete button also don t work  As I was facing the same problem  Came out with the solution   Given Below  Works Perfect for Me  -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string    if textField tag  6         if   textField text length  lt  30                return YES               else if      isEqualToString string                 textField text  textField text substringToIndex 30               return NO      else        return YES         I am having a text field  whose tag I have set  6  and I have restricted the max char limit   30   works fine in every case

User · Answer

now how many characters u want just give values   -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range   replacementString  NSString   string        NSUInteger newLength    textField text length     string length  - range length       return  newLength  gt  25    NO   YES

User · Answer

Swift 4 2   By implementing UITextFieldDelegate method   ViewController   class MyViewController  UIViewController        let MAX LENGTH   256       IBOutlet weak var myTextField  UITextField       override viewDidLoad             self myTextField delegate   self          Delegate   extension MyViewController  UITextFieldDelegate        func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool           let userText    textView text               var newText              if range length  gt  0               let txt   NSString string  userText              if txt length  gt  0                   newText   txt replacingCharacters in  range  with  text                          else               newText   userText   text                   return newText count  lt   MAX LENGTH

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Swift 4  func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool       guard let text   textField text else   return true       let newLength   text count   string count - range length     return newLength  lt   10

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I found this quick and simple  -  IBAction backgroundClick  id sender       if  mytext length  lt   7             mytext resignFirstResponder         else           UIAlertView  alert     UIAlertView alloc  initWithTitle   Too Big                                                           message   Please Shorten Name                                                         delegate nil                                                cancelButtonTitle   Cancel                                                otherButtonTitles nil            alert show            alert release

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You can also do this using NotificationCenter in Swift 4    NotificationCenter default addObserver self  selector   selector self handleTextChange recognizer     name  NSNotification Name UITextFieldTextDidChange  object  yourTextField        objc func handleTextChange recognizer  NSNotification                  max length is 50 charater max             let textField   recognizer object as  UITextField              if  textField text  count    gt  50                    let newString  String     textField text as NSString    substring to  50                  textField text   newString

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For Swift 2 1   func textField textField  UITextField  shouldChangeCharactersInRange range  NSRange  replacementString string  String  - gt  Bool        if  range length   range location  gt  textField text  characters count                 return false             let newLength   textField text  characters count   string characters count - range length     return newLength  lt   25     Hope it helps

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You can t do this directly - UITextField has no maxLength attribute  but you can set the UITextField s delegate  then use   -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string

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Using Interface builder you can link and get the event for  Editing changed  in any of your function  Now there you can put check for the length  -  IBAction onValueChange  id sender        NSString  text   nil      int MAX LENGTH   20      switch   sender tag                   case 1                         text   myEditField text              if  MAX LENGTH  lt   text length                     myEditField text    text substringToIndex MAX LENGTH                                       break          default              break

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Got it down to 1 line of code     Set your text view s delegate to  self  then add the  lt UITextViewDelegate gt  in your  h and the following code in your  m      you can adjust the number  7  to be whatever you want your MAXIMUM number of characters to be    - BOOL textView  UITextView   a shouldChangeTextInRange  NSRange b replacementText  NSString   c       return   a text length c length lt  7   c length lt 1   b length gt  c length  gt 0       This code accounts for typing new characters  deleting characters  selecting characters then typing or deleting  selecting characters and cutting  pasting in general  and selecting characters and pasting   Done       Alternatively  another cool way to write this code with bit-operations would be  - BOOL textView  UITextView   a shouldChangeTextInRange  NSRange b replacementText  NSString   c       return 0   a text length c length lt  7   c length lt 1   b length gt  c length

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While the UITextField class has no max length property  it s relatively simple to get this functionality by setting the text field s delegate and implementing the following delegate method  Objective-C -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string          Prevent crashing undo bug     see note below      if range length   range location  gt  textField text length                return NO                     NSUInteger newLength    textField text length     string length  - range length      return newLength  lt   25     Swift func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool            let currentCharacterCount   textField text  count    0     if range length   range location  gt  currentCharacterCount           return false           let newLength   currentCharacterCount   string count - range length     return newLength  lt   25    Before the text field changes  the UITextField asks the delegate if the specified text should be changed  The text field has not changed at this point  so we grab it s current length and the string length we re inserting  either through pasting copied text or typing a single character using the keyboard   minus the range length  If this value is too long  more than 25 characters in this example   return NO to prohibit the change  When typing in a single character at the end of a text field  the range location will be the current field s length  and range length will be 0 because we re not replacing deleting anything  Inserting into the middle of a text field just means a different range location  and pasting multiple characters just means string has more than one character in it  Deleting single characters or cutting multiple characters is specified by a range with a non-zero length  and an empty string  Replacement is just a range deletion with a non-empty string  A note on the crashing  quot undo quot  bug As is mentioned in the comments  there is a bug with UITextField that can lead to a crash  If you paste in to the field  but the paste is prevented by your validation implementation  the paste operation is still recorded in the application s undo buffer  If you then fire an undo  by shaking the device and confirming an Undo   the UITextField will attempt to replace the string it thinks it pasted in to itself with an empty string  This will crash because it never actually pasted the string in to itself  It will try to replace a part of the string that doesn t exist  Fortunately you can protect the UITextField from killing itself like this  You just need to ensure that the range it proposes to replace does exist within its current string  This is what the initial sanity check above does  swift 3 0 with copy and paste working fine  func textView   textView  UITextView  shouldChangeTextIn range  NSRange  replacementText text  String  - gt  Bool           let str    textView text   text          if str characters count  lt   10               return true                   textView text   str substring to  str index str startIndex  offsetBy  10           return false        Hope it s helpful to you

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Thank you august   Post   This is the code that I ended up with which works    define MAX LENGTH 20  -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string       if  textField text length  gt   MAX LENGTH  amp  amp  range length    0                return NO     return NO to not change text           else      return YES

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This is the correct way to handle max length on UITextField  it allows the return key to exit the resign the textfield as first responder and lets the user backspace when they reach the limit  -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string   int MAX LENGHT   5      if  string isEqualToString    n                   textField resignFirstResponder           return FALSE            else if textField text length  gt  MAX LENGHT-1                if  string isEqualToString       amp  amp  range length    1                        return TRUE                    else                       return FALSE                      else               return TRUE

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Other answers do not handle the case where user can paste a long string from clipboard  If I paste a long string it should just be truncated but shown  Use this in your delegate   static const NSUInteger maxNoOfCharacters   5   - IBAction textdidChange  UITextField    textField   NSString   text   textField text   if text length  gt  maxNoOfCharacters        text    text substringWithRange NSMakeRange 0  maxNoOfCharacters        textField text   text        use  text

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Swift 2 0    First of all create a class for this process  Lets call it StringValidator swift   Then just paste the following code inside it   import Foundation  extension String    func containsCharactersIn matchCharacters  String  - gt  Bool   let characterSet   NSCharacterSet charactersInString  matchCharacters  return self rangeOfCharacterFromSet characterSet     nil    func containsOnlyCharactersIn matchCharacters  String  - gt  Bool   let disallowedCharacterSet   NSCharacterSet charactersInString  matchCharacters  invertedSet return self rangeOfCharacterFromSet disallowedCharacterSet     nil     func doesNotContainCharactersIn matchCharacters  String  - gt  Bool   let characterSet   NSCharacterSet charactersInString  matchCharacters  return self rangeOfCharacterFromSet characterSet     nil    func isNumeric   - gt  Bool   let scanner   NSScanner string  self  scanner locale   NSLocale currentLocale    return scanner scanDecimal nil   amp  amp  scanner atEnd        Now save the class       Usage    Now goto your viewController swift class and make your textfield s outlets as     IBOutlet weak var contactEntryTxtFld  UITextField    First textfield  IBOutlet weak var contactEntryTxtFld2  UITextField      Second textfield   Now goto the textfield s shouldChangeCharactersInRange method and use like the following   func textField textField  UITextField  shouldChangeCharactersInRange range  NSRange  replacementString string  String  - gt  Bool       if string characters count    0           return true           let latestText   textField text           let checkAbleText    latestText as NSString  stringByReplacingCharactersInRange range  withString  string        switch textField        case contactEntryTxtFld          return checkAbleText containsOnlyCharactersIn  0123456789    amp  amp  prospectiveText characters count  lt   5      case contactEntryTxtFld2          return checkAbleText containsOnlyCharactersIn  0123456789    amp  amp  prospectiveText characters count  lt   5      default          return true            Don t forget to set the delegate protocol methods of textfields   Let me explain about this    I am using the simple extension process of string which I wrote inside an another class  Now I am just calling those extension methods from another class where I need them by adding check and maximum value   Features      It will set maximum limit of a particular textfield  It will set type of accepted keys for particular textfield    Types     containsOnlyCharactersIn   Accepts only Characters   containsCharactersIn      Accepts combination of characters  doesNotContainsCharactersIn    Will not accept characters  Hope this helped     Thanks

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This limits the number of characters  but also make sure that you can paste in the field until the maximum limit   -  void textViewDidChange  UITextView   textView       NSString  str    textView text       str    str substringToIndex MIN 1000  str length          textView setText str        if  str length   1000               show some label that you ve reached the limit of 1000 characters

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Swift 4  func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool       guard let text   textField text else   return true       let newLength   text count   string count - range length     return newLength  lt   10

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I simulate the actual string replacement that s about to happen to calculate that future string s length   -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string        NSString  newString    textField text stringByReplacingCharactersInRange range withString string        if  newString length   gt  maxLength         return NO       return YES

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To make it work with cut  amp  paste of strings of any length  I would suggest changing the function to something like     define MAX LENGTH 20  -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string               NSInteger insertDelta   string length - range length           if  textField text length   insertDelta  gt  MAX LENGTH                       return NO     the new string would be longer than MAX LENGTH                   else               return YES

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Using Interface builder you can link and get the event for  Editing changed  in any of your function  Now there you can put check for the length  -  IBAction onValueChange  id sender        NSString  text   nil      int MAX LENGTH   20      switch   sender tag                   case 1                         text   myEditField text              if  MAX LENGTH  lt   text length                     myEditField text    text substringToIndex MAX LENGTH                                       break          default              break

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What about this simple approach  Its working fine for me   extension UITextField        func  charactersLimit to Int             if  self text  count  gt  to                self deleteBackward                       Then   someTextField charactersLimit to 16

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This should be enough to solve the problem  replace 4 by the limit u want   Just make sure to add delegate in IB   -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string        NSString  newString    textField text stringByReplacingCharactersInRange range withString string        return  newString length lt  4

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I simulate the actual string replacement that s about to happen to calculate that future string s length   -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string        NSString  newString    textField text stringByReplacingCharactersInRange range withString string        if  newString length   gt  maxLength         return NO       return YES

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Swift 4 import UIKit  private var kAssociationKeyMaxLength  Int   0  extension UITextField             IBInspectable var maxLength  Int           get               if let length   objc getAssociatedObject self   amp kAssociationKeyMaxLength  as  Int                   return length               else                   return Int max                                 set               objc setAssociatedObject self   amp kAssociationKeyMaxLength  newValue   OBJC ASSOCIATION RETAIN              addTarget self  action   selector checkMaxLength   for   editingChanged                            objc func checkMaxLength textField  UITextField            guard let prospectiveText   self text              prospectiveText count  gt  maxLength             else                   return                            let selection   selectedTextRange                  let indexEndOfText   prospectiveText index prospectiveText startIndex  offsetBy  maxLength          let substring   prospectiveText    lt indexEndOfText          text   String substring                   selectedTextRange   selection          Edit  memory leak issue fixed

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we can set the range of textfield like this    - BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range  replacementString  NSString   string        int setrange   20       return    textField text length  gt setrange  amp  amp   string length   gt  range length

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Use below extension to set the maximum character length of a UITextField and UITextView   Swift 4 0      private var kAssociationKeyMaxLength  Int   0     private var kAssociationKeyMaxLengthTextView  Int   0     extension UITextField              IBInspectable var maxLength  Int               get                   if let length   objc getAssociatedObject self   amp kAssociationKeyMaxLength  as  Int                       return length                   else                       return Int max                                             set                   objc setAssociatedObject self   amp kAssociationKeyMaxLength  newValue   OBJC ASSOCIATION RETAIN                  addTarget self  action   selector checkMaxLength   for   editingChanged                                    objc func checkMaxLength textField  UITextField                guard let prospectiveText   self text                  prospectiveText count  gt  maxLength                 else                       return                            let selection   selectedTextRange              let indexEndOfText   prospectiveText index prospectiveText startIndex  offsetBy  maxLength              let substring   prospectiveText    lt indexEndOfText              text   String substring               selectedTextRange   selection                   UITextView  extension UITextView UITextViewDelegate              IBInspectable var maxLength  Int               get                   if let length   objc getAssociatedObject self   amp kAssociationKeyMaxLengthTextView  as  Int                       return length                   else                       return Int max                                             set                   self delegate   self                  objc setAssociatedObject self   amp kAssociationKeyMaxLengthTextView  newValue   OBJC ASSOCIATION RETAIN                                   public func textViewDidChange   textView  UITextView                checkMaxLength textField  self                     objc func checkMaxLength textField  UITextView                guard let prospectiveText   self text                  prospectiveText count  gt  maxLength                 else                       return                            let selection   selectedTextRange              let indexEndOfText   prospectiveText index prospectiveText startIndex  offsetBy  maxLength              let substring   prospectiveText    lt indexEndOfText              text   String substring               selectedTextRange   selection                   You can set limit below

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The following code is similar to sickp s answer but handles correctly copy-paste operations  If you try to paste a text that is longer than the limit  the following code will truncate the text to fit the limit instead of refusing the paste operation completely   -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string       static const NSUInteger limit   70     we limit to 70 characters     NSUInteger allowedLength   limit -  textField text length    range length      if  string length  gt  allowedLength            if  string length  gt  1                   get at least the part of the new string that fits             NSString  limitedString    string substringToIndex allowedLength               NSMutableString  newString    textField text mutableCopy                newString replaceCharactersInRange range withString limitedString               textField text   newString                    return NO        else           return YES

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There is generic solution for setting max length in Swift  By IBInspectable you can add new Attribute in Xcode Attribute Inspector   import UIKit private var maxLengths    UITextField  Int    extension UITextField         IBInspectable var maxLength  Int           get               guard let length   maxLengths self              else                   return Int max                           return length                   set               maxLengths self    newValue             addTarget                  self                  action  Selector  limitLength                     forControlEvents  UIControlEvents EditingChanged                                    func limitLength textField  UITextField            guard let prospectiveText   textField text             where prospectiveText characters count  gt  maxLength else                   return                   let selection   selectedTextRange         text   prospectiveText substringWithRange              Range lt String Index gt  prospectiveText startIndex    lt  prospectiveText startIndex advancedBy maxLength                     selectedTextRange   selection

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The best way would be to set up a notification on the text changing  In your -awakeFromNib of your view controller method you ll want     NSNotificationCenter defaultCenter  addObserver self selector  selector limitTextField   name   UITextFieldTextDidChangeNotification  object myTextField     Then in the same class add   -  void limitTextField  NSNotification   note       int limit   20      if    myTextField stringValue  length   gt  limit             myTextField setStringValue   myTextField stringValue  substringToIndex limit              Then link up the outlet myTextField to your UITextField and it will not let you add any more characters after you hit the limit  Be sure to add this to your dealloc method     NSNotificationCenter defaultCenter  removeObserver self name   UITextFieldTextDidChangeNotification  object myTextField

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The best way would be to set up a notification on the text changing  In your -awakeFromNib of your view controller method you ll want     NSNotificationCenter defaultCenter  addObserver self selector  selector limitTextField   name   UITextFieldTextDidChangeNotification  object myTextField     Then in the same class add   -  void limitTextField  NSNotification   note       int limit   20      if    myTextField stringValue  length   gt  limit             myTextField setStringValue   myTextField stringValue  substringToIndex limit              Then link up the outlet myTextField to your UITextField and it will not let you add any more characters after you hit the limit  Be sure to add this to your dealloc method     NSNotificationCenter defaultCenter  removeObserver self name   UITextFieldTextDidChangeNotification  object myTextField

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BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string       NSString  newString    textField text stringByReplacingCharactersInRange range withString string        if   txt name text length  gt 100                return NO             return YES

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Use this code here RESTRICTED LENGTH is length you want to restrict for textfield      -  BOOL textField  UITextField   textField     shouldChangeCharactersInRange  NSRange range replacementString  NSString   string       if  textField    nameTF        int limit   RESTRICTED LENGTH - 1      return    textField text length  gt limit  amp  amp   string length   gt  range length            else          return YES        return NO

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I created this UITextFieldLimit subclass    Multiple textfields supported Set the text length limit Paste prevention Displays a label of left characters inside the textfield  get hidden when you stop editing  Shake animation when no characters left    Grab the UITextFieldLimit h and UITextFieldLimit m from this GitHub repository   https   github com JonathanGurebo UITextFieldLimit  and begin to test   Mark your storyboard-created UITextField and link it to my subclass using the Identity Inspector     Then you can link it to an IBOutlet and set the limit default is 10      Your ViewController h file should contain   if you wan t to modify the setting  like the limit    import  UITextFieldLimit h           property  weak  nonatomic  IBOutlet UITextFieldLimit  textFieldLimit      lt --Your IBOutlet     Your ViewController m file should  synthesize textFieldLimit     Set the text length limit in your ViewController m file   -  void viewDidLoad        super viewDidLoad      Do any additional setup after loading the view  typically from a nib        textFieldLimit setLimit 25      lt -- and you won t be able to put more than 25 characters in the TextField      Hope the class helps you  Good luck

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Often you have multiple input fields with a different length   -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string       int allowedLength      switch textField tag            case 1               allowedLength   MAXLENGTHNAME          triggered for input fields with tag   1             break          case 2              allowedLength   MAXLENGTHADDRESS       triggered for input fields with tag   2             break          default              allowedLength   MAXLENGTHDEFAULT       length default when no tag   0  value  255             break             if  textField text length  gt   allowedLength  amp  amp  range length    0            return NO     Change not allowed       else           return YES     Change allowed

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For Xamarin   YourTextField ShouldChangeCharacters    delegate UITextField textField  NSRange range  string replacementString                        return  range Location   replacementString Length   lt   4     MaxLength    4

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now how many characters u want just give values   -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range   replacementString  NSString   string        NSUInteger newLength    textField text length     string length  - range length       return  newLength  gt  25    NO   YES

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Thank you august   Post   This is the code that I ended up with which works    define MAX LENGTH 20  -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string       if  textField text length  gt   MAX LENGTH  amp  amp  range length    0                return NO     return NO to not change text           else      return YES

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swift 3 0 This code is working fine when you are paste string more than your character limits  func textView   textView  UITextView  shouldChangeTextIn range  NSRange  replacementText text  String  - gt  Bool           let str    textView text   text          if str characters count  lt   10               return true                   textView text   str substring to  str index str startIndex  offsetBy  10           return false        Thanks for your votes

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I want to add to the answer given by  sickp   There is an issue in his Swift code that occurs with any multibyte text  e g  emojis   NSRange and String in Swift are not compatible  so it s frustrating that the delegate class combines them  The trick is simply to convert the String objects to NSString The correct solution  based on what  sickp wrote  is actually this   func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool        let currentText    textField text as NSString      NSString       let currentCharacterCount   currentText length     if range length   range location  gt  currentCharacterCount           return false           let newLength   currentText replacingCharacters in  range  with  string  characters count     return newLength  lt   25

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To complete August answer  an possible implementation of the proposed function   see UITextField s delegate    I did not test domness code  but mine do not get stuck if the user reached the limit  and it is compatible with a new string that comes replace a smaller or equal one   - BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string         limit the size       int limit   20      return    textField text length  gt limit  amp  amp   string length   gt  range length

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Slightly beyond answering the original question  and expanding on Frouo s answer  here are extensions to trim a String of whitespace and to a max length  and to utilize those String extensions to trim a UITextField to a max length      In String Extensions swift  extension String      func trimmedString   - gt  String       var trimmedString   self stringByTrimmingCharactersInSet NSCharacterSet whitespaceAndNewlineCharacterSet        let components   trimmedString componentsSeparatedByCharactersInSet NSCharacterSet whitespaceAndNewlineCharacterSet    filter   count  0   gt  0       return     join components         func trimmedStringToMaxLength maxLength  Int  - gt  String       return trimmedString   substringToIndex advance startIndex  min count self   maxLength    trimmedString              In UITextField Extensions swift  private var maxLengthDictionary    UITextField   Int    private var textFieldMaxLength   20  extension UITextField       IBInspectable var maxLength  Int       get         if let maxLength   maxLengthDictionary self            return maxLength         else           return textFieldMaxLength                   set         maxLengthDictionary self    newValue  lt  textFieldMaxLength   1   newValue   textFieldMaxLength              func trimAndLimitToMaxLength         text   text trimmedStringToMaxLength maxLength          let someTextField   UITextField   let someString       This   is   a   string   that   is longer than allowable for a text field      someTextField text   someString someTextField trimAndLimitToMaxLength   println someTextField text     Prints  This is a string tha  let anotherTextField   UITextField   anotherTextField maxLength   5 anotherTextField text   someString anotherTextField trimAndLimitToMaxLength   println anotherTextField text     Prints  This    trimAndLimitToMaxLength   could be used in UITextFieldDelegate s textFieldDidEndEditing     so that a user could enter or paste in a longer than acceptable string and then shorten it vs  just cutting off the input at the max length  In doing this  I would also set attributed text styles to indicate any portion of the text that goes beyond the acceptable length  e g    NSBackgroundColorAttributeName   UIColor redColor    NSForegroundColorAttributeName   UIColor whiteColor    NSStrikethroughStyleAttributeName   NSNumber int  1

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Swift 4 2 and UITextFieldDelegate method  This works for me and limits the textfield to have a max input of 8 characters  Hopefully NSRange will eventually be changed to Range but for now I am happy to use NSString as creating a Range from NSRange involves dealing with another optional   func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool       let text   textField text           let nsString   text as NSString     let newText   nsString replacingCharacters in  range  with  string      return newText count  lt   8

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If your purpose of limiting text count is to ensure that text will fit into a UILabel elsewhere  I d avoid using character count  It breaks down with some emoji  trying to truncate a double size emoji will likely crash your app   It s also an issue with some languages like Japanese and Chinese  which have a two-step input process where a simple count just won t work    I built out a UITextField drop-in subclass  MPC CharacterLimitedTextField on github   You feed it the expected output label width and it will handle all languages  emoji  and pasting issues  It will harvest only as many full characters that will fit into the label  regardless of the character count  There s a demo in the project so you can test it to see if it s what you need  Hope it will help anybody who was having the same problems with output length that I was

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While the UITextField class has no max length property  it s relatively simple to get this functionality by setting the text field s delegate and implementing the following delegate method  Objective-C -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string          Prevent crashing undo bug     see note below      if range length   range location  gt  textField text length                return NO                     NSUInteger newLength    textField text length     string length  - range length      return newLength  lt   25     Swift func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool            let currentCharacterCount   textField text  count    0     if range length   range location  gt  currentCharacterCount           return false           let newLength   currentCharacterCount   string count - range length     return newLength  lt   25    Before the text field changes  the UITextField asks the delegate if the specified text should be changed  The text field has not changed at this point  so we grab it s current length and the string length we re inserting  either through pasting copied text or typing a single character using the keyboard   minus the range length  If this value is too long  more than 25 characters in this example   return NO to prohibit the change  When typing in a single character at the end of a text field  the range location will be the current field s length  and range length will be 0 because we re not replacing deleting anything  Inserting into the middle of a text field just means a different range location  and pasting multiple characters just means string has more than one character in it  Deleting single characters or cutting multiple characters is specified by a range with a non-zero length  and an empty string  Replacement is just a range deletion with a non-empty string  A note on the crashing  quot undo quot  bug As is mentioned in the comments  there is a bug with UITextField that can lead to a crash  If you paste in to the field  but the paste is prevented by your validation implementation  the paste operation is still recorded in the application s undo buffer  If you then fire an undo  by shaking the device and confirming an Undo   the UITextField will attempt to replace the string it thinks it pasted in to itself with an empty string  This will crash because it never actually pasted the string in to itself  It will try to replace a part of the string that doesn t exist  Fortunately you can protect the UITextField from killing itself like this  You just need to ensure that the range it proposes to replace does exist within its current string  This is what the initial sanity check above does  swift 3 0 with copy and paste working fine  func textView   textView  UITextView  shouldChangeTextIn range  NSRange  replacementText text  String  - gt  Bool           let str    textView text   text          if str characters count  lt   10               return true                   textView text   str substring to  str index str startIndex  offsetBy  10           return false        Hope it s helpful to you

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Swift 2 0    First of all create a class for this process  Lets call it StringValidator swift   Then just paste the following code inside it   import Foundation  extension String    func containsCharactersIn matchCharacters  String  - gt  Bool   let characterSet   NSCharacterSet charactersInString  matchCharacters  return self rangeOfCharacterFromSet characterSet     nil    func containsOnlyCharactersIn matchCharacters  String  - gt  Bool   let disallowedCharacterSet   NSCharacterSet charactersInString  matchCharacters  invertedSet return self rangeOfCharacterFromSet disallowedCharacterSet     nil     func doesNotContainCharactersIn matchCharacters  String  - gt  Bool   let characterSet   NSCharacterSet charactersInString  matchCharacters  return self rangeOfCharacterFromSet characterSet     nil    func isNumeric   - gt  Bool   let scanner   NSScanner string  self  scanner locale   NSLocale currentLocale    return scanner scanDecimal nil   amp  amp  scanner atEnd        Now save the class       Usage    Now goto your viewController swift class and make your textfield s outlets as     IBOutlet weak var contactEntryTxtFld  UITextField    First textfield  IBOutlet weak var contactEntryTxtFld2  UITextField      Second textfield   Now goto the textfield s shouldChangeCharactersInRange method and use like the following   func textField textField  UITextField  shouldChangeCharactersInRange range  NSRange  replacementString string  String  - gt  Bool       if string characters count    0           return true           let latestText   textField text           let checkAbleText    latestText as NSString  stringByReplacingCharactersInRange range  withString  string        switch textField        case contactEntryTxtFld          return checkAbleText containsOnlyCharactersIn  0123456789    amp  amp  prospectiveText characters count  lt   5      case contactEntryTxtFld2          return checkAbleText containsOnlyCharactersIn  0123456789    amp  amp  prospectiveText characters count  lt   5      default          return true            Don t forget to set the delegate protocol methods of textfields   Let me explain about this    I am using the simple extension process of string which I wrote inside an another class  Now I am just calling those extension methods from another class where I need them by adding check and maximum value   Features      It will set maximum limit of a particular textfield  It will set type of accepted keys for particular textfield    Types     containsOnlyCharactersIn   Accepts only Characters   containsCharactersIn      Accepts combination of characters  doesNotContainsCharactersIn    Will not accept characters  Hope this helped     Thanks

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I give a supplementary answer based on  Frouo   I think his answer is the most beautiful way  Becuase it s a common control we can reuse    private var kAssociationKeyMaxLength  Int   0  extension UITextField         IBInspectable var maxLength  Int           get               if let length   objc getAssociatedObject self   amp kAssociationKeyMaxLength  as  Int                   return length               else                   return Int max                                 set               objc setAssociatedObject self   amp kAssociationKeyMaxLength  newValue   OBJC ASSOCIATION RETAIN              self addTarget self  action   selector checkMaxLength   for   editingChanged                       func checkMaxLength textField  UITextField             guard  self isInputMethod    let prospectiveText   self text              prospectiveText count  gt  maxLength             else                   return                    let selection   selectedTextRange         let maxCharIndex   prospectiveText index prospectiveText startIndex  offsetBy  maxLength          text   prospectiveText substring to  maxCharIndex          selectedTextRange   selection              The method is used to cancel the check when use Chinese Pinyin input method        Becuase the alphabet also appears in the textfield when inputting  we should cancel the check      func isInputMethod   - gt  Bool           if let positionRange   self markedTextRange               if let     self position from  positionRange start  offset  0                    return true                                 return false

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for Swift 3 1 or later  firstly add protocol UITextFieldDelegate   like -  class PinCodeViewController  UIViewController  UITextFieldDelegate                           after that create your UITextField and set delegate  Complete Exp  -  import UIKit  class PinCodeViewController  UIViewController  UITextFieldDelegate    let pinCodetextField  UITextField         let tf   UITextField       tf placeholder    please enter your pincode      tf font   UIFont systemFont ofSize  15      tf borderStyle   UITextBorderStyle roundedRect     tf autocorrectionType   UITextAutocorrectionType no     tf keyboardType   UIKeyboardType numberPad     tf clearButtonMode   UITextFieldViewMode whileEditing      tf contentVerticalAlignment   UIControlContentVerticalAlignment center  return tf          override func viewDidLoad        super viewDidLoad      view addSubview pinCodetextField        ----- setup your textfield anchor or position where you want to show it-----           after that  pinCodetextField delegate   self    setting the delegate     func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool       return   textField text  characters count    6  amp  amp  string                  this is return the maximum characters in textfield

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Swift 3 version         This will NOT work with Swift 2 x           First create a new Swift file   TextFieldMaxLength swift  and then add the code below   import UIKit  private var maxLengths    UITextField  Int     extension UITextField        IBInspectable var maxLength  Int          get              guard let length   maxLengths self                else                   return Int max               return length         set         maxLengths self    newValue       addTarget           self           action   selector limitLength            for  UIControlEvents editingChanged                func limitLength textField  UITextField        guard let prospectiveText   textField text          prospectiveText characters count  gt  maxLength     else           return           let selection   selectedTextRange    let maxCharIndex   prospectiveText index prospectiveText startIndex  offsetBy  maxLength     text   prospectiveText substring to  maxCharIndex     selectedTextRange   selection          and then you will see in Storyboard a new field  Max Length  when you select any TextField  if you still have more questions check out this link  http   www globalnerdy com 2016 05 18 ios-programming-trick-how-to-use-xcode-to-set-a-text-fields-maximum-length-visual-studio-style

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Other answers do not handle the case where user can paste a long string from clipboard  If I paste a long string it should just be truncated but shown  Use this in your delegate   static const NSUInteger maxNoOfCharacters   5   - IBAction textdidChange  UITextField    textField   NSString   text   textField text   if text length  gt  maxNoOfCharacters        text    text substringWithRange NSMakeRange 0  maxNoOfCharacters        textField text   text        use  text

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This limits the number of characters  but also make sure that you can paste in the field until the maximum limit   -  void textViewDidChange  UITextView   textView       NSString  str    textView text       str    str substringToIndex MIN 1000  str length          textView setText str        if  str length   1000               show some label that you ve reached the limit of 1000 characters

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You can t do this directly - UITextField has no maxLength attribute  but you can set the UITextField s delegate  then use   -  BOOL textField  UITextField   textField shouldChangeCharactersInRange  NSRange range replacementString  NSString   string

[ios] Set the maximum character length of a UITextField

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