Max length UITextField

Question

When I ve tried How to you set the maximum number of characters that can be entered into a UITextField using swift   I saw that if I use all 10 characters  I can t erase the character too   The only thing I can do is to cancel the operation  delete all the characters together    Does anyone know how to not block the keyboard  so that I can t add other letters symbols numbers  but I can use the backspace

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If you want to overwrite the last letter   let maxLength   10  func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool        if range location  gt  maxLength - 1           textField text  removeLast              return true

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Update for 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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func checkMaxLength textField  UITextField   maxLength  Int            if  textField text  characters count  gt  maxLength                textField deleteBackward                 a small change for IOS 9

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Swift 5 func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool           let MAX LENGTH   4         let updatedString    textField text  as NSString  replacingCharacters in  range  with  string          return updatedString count  lt   MAX LENGTH

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I have been using this protocol   extension in one of my apps  and it s a little more readable  I like how it recognizes backspaces and explicitly tells you when a character is a backspace   Some things to consider   1 Whatever implements this protocol extension needs to specify a character limit  That s typically going to be your ViewController  but you could implement character limit as a computed property and return something else  for example a character limit on one of your models   2  You will need to call this method inside of your text field s shouldChangeCharactersInRange delegate method  Otherwise you won t be able to block text entry by returning false  etc   3  You will probably want to allow backspace characters through  That s why I added the extra function to detect backspaces  Your shouldChangeCharacters method can check for this and return  true  early on so you always allow backspaces   protocol TextEntryCharacterLimited      var characterLimit Int   get       extension TextEntryCharacterLimited       func charactersInTextField textField UITextField  willNotExceedCharacterLimitWithReplacementString string String  range NSRange  - gt  Bool           let startingLength   textField text  characters count    0         let lengthToAdd   string characters count         let lengthToReplace   range length          let newLength   startingLength   lengthToAdd - lengthToReplace          return newLength  lt   characterLimit             func stringIsBackspaceWith string String  inRange range NSRange  - gt  Bool          if range length    1  amp  amp  string characters count    0   return true           return false            If any of you are interested  I have a Github repo where I ve taken some of this character limit behavior and put into an iOS framework  There s a protocol you can implement to get a Twitter-like character limit display that shows you how far you ve gone above the character limit   CharacterLimited Framework on Github

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In Swift 4   10 Characters limit for text field and allow to delete backspace   func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool           if textField     userNameFTF              let char   string cString using  String Encoding utf8              let isBackSpace   strcmp char     b               if isBackSpace    -92                   return true                           return textField text  count  lt   9                   return true

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I posted a solution using IBInspectable  so you can change the max length value both in interface builder or programmatically  Check it out here

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Add More detail from  Martin answer     linked your button here  IBAction func mobileTFChanged sender  AnyObject        checkMaxLength sender as  UITextField  maxLength  10        linked your button here  IBAction func citizenTFChanged sender  AnyObject        checkMaxLength sender as  UITextField  maxLength  13     func checkMaxLength textField  UITextField   maxLength  Int           swift 1 0       if  count textField text    gt  maxLength              textField deleteBackward                  swift 2 0     if  textField text  characters count  gt  maxLength            textField deleteBackward

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Swift 3  func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool                let nsString   NSString string  textField text               let newText   nsString replacingCharacters in  range  with  string              return  newText characters count  lt   limitCount

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you can extend UITextField and add an  IBInspectable object for handle it   SWIFT 5  import UIKit private var   maxLengths    UITextField  Int    extension UITextField        IBInspectable var maxLength  Int           get               guard let l     maxLengths self  else                   return 150     global default-limit  or just  Int max                            return l                   set                 maxLengths self    newValue             addTarget self  action   selector fix   for   editingChanged                       objc func fix textField  UITextField            if let t   textField text               textField text   String t prefix maxLength                       and after that define it on attribute inspector    See Swift 4 original Answer

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Since delegates are a 1-to-1 relationship and I might want to use it elsewhere for other reasons  I like to restrict textfield length adding this code within their setup       required init coder aDecoder  NSCoder            super init coder  aDecoder           setup              required override init frame  CGRect            super init frame  frame          setup              func setup                 your setup             setMaxLength              let maxLength   10      private func setMaxLength                 addTarget self  action   selector textfieldChanged       for  UIControlEvents editingChanged                      objc private func textfieldChanged   textField  UITextField                guard let text   text else   return               let trimmed   text characters prefix maxLength              self text   String trimmed

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Here is my version of code  Hope it helps       func textField textField  UITextField  shouldChangeCharactersInRange range  NSRange  replacementString string  String  - gt  Bool           let invalidCharacters   NSCharacterSet charactersInString   0123456789   invertedSet          if let range   string rangeOfCharacterFromSet invalidCharacters  options  nil  range Range lt String Index gt  start  string startIndex  end  string endIndex                         return false                    if  count textField text   gt  10   amp  amp  range length    0                        self view makeToast message   Amount entry is limited to ten digits   duration  0 5  position  HRToastPositionCenter              return false                   else                               return true

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Im using this   Limit 3 char  func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool            if let txt   textField text               let currentText   txt   string             if currentText count  gt  3                   return false                           return true                   return true

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You can use in swift 5 or swift 4 like  image look like bellow    Add textField in View Controller Connect to text to ViewController   add the code in view ViewController    class ViewController  UIViewController   UITextFieldDelegate       IBOutlet weak var txtName  UITextField     var maxLen Int   8    override func viewDidLoad         super viewDidLoad        txtName delegate   self        func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool         if textField    txtName           let currentText   textField text    string         return currentText count  lt   maxLen              return true            You can download Full Source form GitHub  https   github com enamul95 TextFieldMaxLen

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With Swift 5 and iOS 12  try the following implementation of textField   shouldChangeCharactersIn replacementString   method that is part of the UITextFieldDelegate protocol   func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool       guard let textFieldText   textField text          let rangeOfTextToReplace   Range range  in  textFieldText  else               return false           let substringToReplace   textFieldText rangeOfTextToReplace      let count   textFieldText count - substringToReplace count   string count     return count  lt   10      The most important part of this code is the conversion from range  NSRange  to rangeOfTextToReplace  Range lt String Index gt    See this video tutorial to understand why this conversion is important  To make this code work properly  you should also set the textField s smartInsertDeleteType value to UITextSmartInsertDeleteType no  This will prevent the possible insertion of an  unwanted  extra space when performing a paste operation      The complete sample code below shows how to implement textField   shouldChangeCharactersIn replacementString   in a UIViewController   import UIKit  class ViewController  UIViewController  UITextFieldDelegate         IBOutlet var textField  UITextField     Link this to a UITextField in Storyboard      override func viewDidLoad             super viewDidLoad            textField smartInsertDeleteType   UITextSmartInsertDeleteType no         textField delegate   self            func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool           guard let textFieldText   textField text              let rangeOfTextToReplace   Range range  in  textFieldText  else                   return false                   let substringToReplace   textFieldText rangeOfTextToReplace          let count   textFieldText count - substringToReplace count   string count         return count  lt   10

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Beware of the undo bug for UITextField mentioned in this post  Set the maximum character length of a UITextField  here is how you fix it in swift   if range length   range location  gt  count textField text             return false

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You need to check whether the existing string plus the input is greater than 10       func textField textField  UITextField  shouldChangeCharactersInRange range  NSRange     replacementString string  String   - gt  Bool         NSUInteger newLength   textField text length   string length - range length        return   newLength  gt  10

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I do it like this   func checkMaxLength textField  UITextField   maxLength  Int        if  countElements textField text    gt  maxLength            textField deleteBackward             The code works for me  But I work with storyboard  In Storyboard I add an action for the text field in the view controller on editing changed

[ios] Max length UITextField

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