How to restrict UITextField to take only numbers in Swift

Question

I want the user to only enter numeric values in a UITextField  On iPhone we can show the numeric keyboard  but on iPad the user can switch to any keyboard   Is there  any way to restrict user to enter only numeric values in a UITextField

User · Answer

You can use this code if you want to allow decimal separator and/or negative numbers. But this code allows example: "34." (decimal separator at the end) while changing text. So you have to add some code example: textFieldShouldReturn or textFieldShouldEndEditing delegate functions.

The code written in Swift 4 but I assueme this is compatible with Swift 3.

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    guard let text = textField.text else {
        return true
    }

    let replaced = (text as NSString).replacingCharacters(in: range, with: string)
    let decimalSeparator = NSLocale.current.decimalSeparator ?? ""

    // When user wants to delete las character
    if replaced == "" || replaced == "-" || replaced == "-0" {
        textField.text = "0"
        return false
    }

    // When text contains 0 before replace except "0."
    if replaced != "0" + decimalSeparator && replaced.hasPrefix("0") && text.underestimatedCount == 1 {
        textField.text = replaced.substring(from: replaced.index(after: replaced.startIndex))
        return false
    }

    // When user wants to delete minus sign
    if text.hasPrefix("-") && text.substring(from: text.index(after: text.startIndex)) == replaced {
        return false
    }

    // When user wants to delete before decimal separator
    if replaced.hasPrefix(decimalSeparator) || replaced.hasPrefix("-" + decimalSeparator) {
        return false
    }

    // When user wants to add zero the beginning of number... but allowing "0." or "-0." numbers
    let testReplaced = replaced.hasPrefix("-") ? replaced.substring(from: replaced.index(after: replaced.startIndex)) : replaced
    if testReplaced.count >= 2 && testReplaced.hasPrefix("0") && !testReplaced.hasPrefix("0" + decimalSeparator) {
        return false
    }

    // Every other cases
    let allowDecimal = self.allowFloat ? (decimalSeparator == "." ? "\\.?" : decimalSeparator + "?") : ""
    let allowSign = self.allowSigned ? "-?" : ""
    let pattern = "\(allowSign)[0-9]+\(allowDecimal)([0-9]+)?"

    do {
        let regexRange = (replaced as NSString).range(of: replaced)
        let regex = try NSRegularExpression(pattern: pattern, options: [])
        let matches = regex.matches(in: replaced, options: [], range: regexRange)
        return matches.count == 1 && matches.first!.range == regexRange
    }
    catch {}

    return false
}

If you don't want to allow decimal or negative numbers you have to replace tow variable with next line

let allowDecimal = ""
let allowSign = ""

User · Answer

You can use shouldChangeCharactersInRange along with String extension method to check if the input string is number or not    extension String         var isNumber   Bool           get              return  self isEmpty  amp  amp  self stringWithoutWhitespaces rangeOfCharacter from  CharacterSet decimalDigits inverted     nil                      var stringWithoutWhitespaces  String           return self replacingOccurrences of       with                  Mark  shouldChangeCharactersInRange func textField textField  UITextField  shouldChangeCharactersInRange range  NSRange  replacementString string  String  - gt  Bool          return true if the string only contains numeric characters     let isValid   string stringWithoutWhitespaces isNumber      return valid

User · Answer

While most of these solutions will work  be aware that in some localisations a decimals are separated with a     and not a      The cleaner way to do this would be  func textField textField  UITextField  shouldChangeCharactersInRange range  NSRange  replacementString string  String  - gt  Bool       let decimalCharacter   NSNumberFormatter   decimalSeparator     let characterSet   NSMutableCharacterSet decimalDigitCharacterSet       characterSet addCharactersInString decimalCharacter       return replacementString rangeOfCharacterFromSet characterSet invertedSet     nil

User · Answer

Only accept decimal numbers as input    SWIFT 3 0    func textField   shouldChangeCharactersIntextField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool           let inverseSet   NSCharacterSet charactersIn  0123456789   inverted          let components   string components separatedBy  inverseSet           let filtered   components joined separator               return string    filtered

User · Answer

For allow some charactors  func CheckAddress string String  - gt  Bool            let numberOnly   NSCharacterSet init charactersIn   0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-   amp              let stringFromTextField   NSCharacterSet init charactersIn  string          return numberOnly isSuperset of  stringFromTextField as CharacterSet         print    CheckAddress string   123        True print    CheckAddress string   asdf-        True print    CheckAddress string   asd123         false

User · Answer

Use number formatter  Swift 4 x    func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool         let s   NSString string  textField text        replacingCharacters in  range  with  string        guard  s isEmpty else   return true         let numberFormatter   NumberFormatter         numberFormatter numberStyle    none       return numberFormatter number from  s   intValue    nil

User · Answer

As if there aren t enough answers  here s mine  I think every example allowed for decimal separators is flawed in either localization  backspaces  or copy paste   func textField textField  UITextField  shouldChangeCharactersInRange range  NSRange  replacementString string  String  - gt  Bool       if string isEmpty  return true    allow for backspace      let decimalSeparator   NSNumberFormatter   decimalSeparator            let validChars   NSMutableCharacterSet charactersInString  decimalSeparator      validChars formUnionWithCharacterSet NSCharacterSet decimalDigitCharacterSet         if validChars isSupersetOfSet NSCharacterSet charactersInString  string            switch string componentsSeparatedByString decimalSeparator  count-1           case 0    no decimals             return true          case 1    if adding decimal  only allow if no existing decimal             if let existingText   textField text                  return existingText componentsSeparatedByString decimalSeparator  count  lt   1                           else  return true           default    invalid decimals             return false                      return false

User · Answer

Here is my 2 Cents   Tested on Swift 2 Only   func textField textField  UITextField  shouldChangeCharactersInRange range  NSRange  replacementString string  String  - gt  Bool      let aSet   NSCharacterSet charactersInString  0123456789   invertedSet   let compSepByCharInSet   string componentsSeparatedByCharactersInSet aSet    let numberFiltered   compSepByCharInSet joinWithSeparator       return string    numberFiltered      This is just a little bit more strict  No decimal point either   Hope it helps      PS  I assumed you looked after the delegate anyway   Update  Swift 3 0    func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool        let aSet   NSCharacterSet charactersIn  0123456789   inverted     let compSepByCharInSet   string components separatedBy  aSet      let numberFiltered   compSepByCharInSet joined separator          return string    numberFiltered

User · Answer

1st you have to inherit the UITextFieldDelegate class with you own   class   class ViewController  UIViewController  UITextFieldDelegate        2nd add an IBOutlet    IBOutlet weak var firstName  UITextField       3rd you have to assure this object is using   override func viewDidLoad             super viewDidLoad      firstName delegate   self     func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool       if textField    firstName                   let allowedCharacters    1234567890                  let allowedCharacterSet   CharacterSet charactersIn  allowedCharacters                  let typedCharacterSet   CharacterSet charactersIn  string                  let alphabet   allowedCharacterSet isSuperset of  typedCharacterSet                  return alphabet

User · Answer

I have edited Raj Joshi s version to allow one dot or one comma   func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool        let inverseSet   CharacterSet charactersIn  0123456789   inverted     let components   string components separatedBy  inverseSet      let filtered   components joined separator           if filtered    string           return true       else           if string           string                      let countDots   textField text  components separatedBy      count - 1             let countCommas   textField text  components separatedBy      count - 1              if countDots    0  amp  amp  countCommas    0                   return true               else                   return false                         else                return false

User · Answer

Here is a simple solution  you need to connect the event  Editing changed  to this method in your controller  Swift 4   IBAction func valueChanged   sender  UITextField        if let last   sender text  last           let zero  Character    0          let num  Int   Int UnicodeScalar String last    value - UnicodeScalar String zero    value          if  num  lt  0    num  gt  9                  remove the last character as it is invalid             sender text  removeLast

User · Answer

Accept decimal values in text fields with single    dot in Swift 3  func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool       let inverseSet   NSCharacterSet charactersIn  0123456789   inverted      let components   string components separatedBy  inverseSet       let filtered   components joined separator           if filtered    string           return true       else           if string                      let countdots   textField text  components separatedBy      count - 1             if countdots    0                   return true              else                  if countdots  gt  0  amp  amp  string                              return false                   else                       return true                                          else              return false

User · Answer

Dead simple solution for Double numbers  keep it mind that this is not the best user-friendly solution   in your UITextFieldDelegate delegate   func textField   textField  UITextField                 shouldChangeCharactersIn range  NSRange                 replacementString string  String  - gt  Bool           guard let currentString   textField text as NSString  else               return false                   let newString   currentString replacingCharacters in  range  with  string          return Double newString     nil

User · Answer

An approach that solves both decimal and Int   func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool       let currentText   textField text     let futureString   currentText substring toIndex  range location    string   currentText substring fromIndex  range location   range length           if futureString count    0           return true                if isDecimal           if let numberAsDouble   Double futureString   numberAsDouble asPrice count  gt   futureString count               return true                 else if let numberAsInt   Int futureString    quot   numberAsInt  quot  count    futureString count           return true                return false

User · Answer

Swift 2 0  For only allowing numbers and one     decimal in uitextfield   func textField textField  UITextField shouldChangeCharactersInRange range  NSRange replacementString string  String  - gt  Bool       let newCharacters   NSCharacterSet charactersInString  string      let boolIsNumber   NSCharacterSet decimalDigitCharacterSet   isSupersetOfSet newCharacters      if boolIsNumber    true           return true       else           if string                      let countdots   textField text  componentsSeparatedByString      count - 1             if countdots    0                   return true               else                   if countdots  gt  0  amp  amp  string                              return false                   else                       return true                                           else               return false

User · Answer

func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool                        let textString    textField text  as NSString  replacingCharacters in  range  with  string               if textField    self phoneTextField   amp  amp  string characters count  gt  0                  let numberOnly   NSCharacterSet decimalDigits                 let strValid   numberOnly contains UnicodeScalar init string                    return strValid  amp  amp  textString characters count  lt   10                           return true             in above code is working in swift 3  NSCharacterSet decimalDigits You are also use letters only  NSCharacterSet Letters and uppercase Lowercaseand alphanumerics whitespaces is used same code  or  See the Link

User · Answer

Updated Cian s response above to Swift 3   func textField textField  UITextField shouldChangeCharactersInRange range  NSRange replacementString string  String  - gt  Bool       let newCharacters   NSCharacterSet charactersIn  string      let boolIsNumber   NSCharacterSet decimalDigits isSuperset of newCharacters as CharacterSet      if boolIsNumber    true           return true       else           if string                      let countdots   textField text  components separatedBy      count - 1             if countdots    0                   return true               else                   if countdots  gt  0  amp  amp  string                              return false                   else                       return true                                           else               return false

User · Answer

Swift 3       func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool       if textField  yourTextFieldOutlet                   if CharacterSet decimalDigits isSuperset of  CharacterSet charactersIn  yourTextFieldOutlet text        if numbers only  then your code here                                   else                  showAlert title   Error  message   Enter Number only  type   failure                                       return true

User · Answer

Solution for swift 3 0 and above func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool       let allowedCharacters   CharacterSet decimalDigits     let characterSet   CharacterSet charactersIn  string      return allowedCharacters isSuperset of  characterSet

User · Answer

The following is the code I used in Swift 3 0 adapted from Mr H s code  Differences are because   a  Delegate function declaration has changed in Swift 3 0  New declaration here  b  NSCharacterSet declaration has changed   func textField   shouldChangeCharactersIntextField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool            let inverseSet   NSCharacterSet charactersIn  0123456789   inverted          let components   string components separatedBy  inverseSet           let filtered   components joined separator               return string    filtered

User · Answer

In swift 4 1 and Xcode 9 4 1  Add UITextFieldDelegate to your class  class YourViewController  UIViewController  UITextFieldDelegate   Then write this code in your viewDidLoad    mobileNoTF delegate   self   Write this textfield delegate function    MARK - UITextField Delegates func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool         For mobile numer validation     if textField    mobileNoTF           let allowedCharacters   CharacterSet charactersIn   0123456789     Here change this characters based on your requirement         let characterSet   CharacterSet charactersIn  string          return allowedCharacters isSuperset of  characterSet            return true

User · Answer

The following solution has two benefits   It is a one line code It restricts the input so that the overall text in the input field is a valid number  Other solutions restricts the digits to valid numbers but this results in the user is able to enter  quot 4   5 quot       func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool           return NumberFormatter   numberFrom text   textField text     quot  quot     string     nil

User · Answer

func textField textField  UITextField  shouldChangeCharactersInRange range  NSRange  replacementString string  String  - gt  Bool       if let numRange   string rangeOfCharacterFromSet NSCharacterSet letterCharacterSet              return false       else           return true

User · Answer

I think you can force change the keyboard type by implementing UITextInputTraits protocol  optional var keyboardType    class ViewController  UIViewController  UITextInputTraits     IBOutlet weak var textFieldKeyboardType  UITextField       didSet          textFieldKeyboardType keyboardType   UIKeyboardType NumberPad         var keyboardType  UIKeyboardType        get           return textFieldKeyboardType keyboardType            set           if newValue    UIKeyboardType NumberPad              self keyboardType   UIKeyboardType NumberPad

User · Answer

Swift 2 0  func textField textField  UITextField      shouldChangeCharactersInRange range  NSRange      replacementString string  String  - gt  Bool            let inverseSet   NSCharacterSet charactersInString  0123456789   invertedSet          let components   string componentsSeparatedByCharactersInSet inverseSet           let filtered   components joinWithSeparator              return string    filtered

User · Answer

Tested in swift 3 0  func textField textField  UITextField  shouldChangeCharactersInRange range  NSRange  replacementString string  String  - gt  Bool                 let numberOnly   NSCharacterSet init charactersIn   0123456789       let stringFromTextField   NSCharacterSet init charactersIn  string      let strValid   numberOnly isSuperset of  stringFromTextField as CharacterSet        return strValid

User · Answer

func isValidNumber str String  - gt  Bool      if str isEmpty           return false           let newChar   NSCharacterSet charactersInString  str      let boolValid   NSCharacterSet decimalDigitCharacterSet   isSupersetOfSet newChar      if boolValid          return true      else          let lst   str componentsSeparatedByString              let newStr   lst joinWithSeparator             let currentChar   NSCharacterSet charactersInString  newStr          if lst count    2  amp  amp   lst contains      amp  amp  NSCharacterSet decimalDigitCharacterSet   isSupersetOfSet currentChar               return true                   return false           Put this function in your  Submit  or  Save  method if there is one

User · Answer

To allow only numbers and just one decimal operator  you can use this solution   func textField textField  UITextField  shouldChangeCharactersInRange range  NSRange  replacementString string  String  - gt  Bool       let isNumber   NSCharacterSet decimalDigitCharacterSet   isSupersetOfSet NSCharacterSet charactersInString  string        return isNumber     string    NSNumberFormatter   decimalSeparator  amp  amp  textField text  containsString string     false

User · Answer

Extend your view controller like this   class MyViewController  UIViewController  UITextFieldDelegate   In the viewDidLoad function extend to your text field like this   myTextField delegate   self   And then use the following function   func textField   textField  UITextField  shouldChangeCharactersIn range  NSRange  replacementString string  String  - gt  Bool       let isNumber   CharacterSet decimalDigits isSuperset of  CharacterSet charactersIn  string       let withDecimal             string    NumberFormatter   decimalSeparator  amp  amp          textField text  contains string     false           return isNumber    withDecimal     This will now make sure the user can enter only decimal digits   Swift 4   Accepts Number only and accepts one separator

User · Answer

Here s an cleaner solution     guard CharacterSet charactersIn   123456789   isSuperset of  CharacterSet charactersIn  string   else        return false     return true   For decimals just add    example 123456789

User · Answer

Set KeyboardType  Property  - Number Pad  TextField Delegate please write below code     func textField   textField  UITextField  shouldChangeCharactersIn    range  NSRange  replacementString string  String  - gt  Bool        if textField text  count    0  amp  amp  string     0            return false           return string    string filter  0123456789  contains      Number should not start from 0  and entered number  ve

User · Answer

First add delegate and keyBoradType of textField  textField delegate self  textField keyboardType   UIKeyboardTypeNumberPad   Than have to use the textField delegate method like so -  -  BOOL  textField   UITextField   theTextField shouldChangeCharactersInRange  NSRange range replacementString   NSString   string      if   string length             return YES         if   string intValue               return YES         return NO

User · Answer

IPhone only solution  In whatever UITextField you re getting these values from  you can specify the kind of keyboard you want to appear when somebody touches inside the text field   E G  a numeric-only keyboard   Like this screenshot     Ipad  The iPad does not support the numeric keyboard  so your options are to either not support the iPad  validate the field post submit  or follow one of the other suggestions here to create same behaviors while running on an iPad

User · Answer

I had actually done this when working through the Big Nerd Ranch book  my solution is   func textField textField  UITextField       shouldChangeCharactersInRange range  NSRange       replacementString string  String  - gt  Bool        let newCharacters   NSCharacterSet charactersInString  string      return NSCharacterSet decimalDigitCharacterSet   isSupersetOfSet newCharacters      this only allows the numbers 0-9  to allow the     as well is more complicated as you can only allow one

User · Answer

This is a more readable version that will do  0-9  plus       func textField textField  UITextField  shouldChangeCharactersInRange range  NSRange  replacementString string  String  - gt  Bool        let existingTextHasDecimal   textField text  rangeOfString          let replacementTextHasDecimal   string rangeOfString          let replacementTextAllCharacters   NSCharacterSet charactersInString  string      let replacementTextOnlyDigits   NSCharacterSet decimalDigitCharacterSet   isSupersetOfSet replacementTextAllCharacters       if replacementTextHasDecimal    nil  amp  amp  existingTextHasDecimal    nil           return false      else          if replacementTextOnlyDigits    true               return true          else if replacementTextHasDecimal    nil              return true          else              return false

User · Answer

func textField textField  UITextField  shouldChangeCharactersInRange range  NSRange  replacementString string  String  - gt  Bool          return true if the replacementString only contains numeric characters     let digits   NSCharacterSet decimalDigitCharacterSet       for c in string           if  digits characterIsMember c                return false                      return true     This solution will work even if the user switches keyboards or tries to paste a non-numeric string into the text field   Make sure to set the delegate property of the appropriate text field

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