Limit UITextField input for numbers in Swift

Question

How can I get a TextField user login restriction on numbers in Swift?

Answer 1

You can use the UITextFieldDelegates method shouldChangeCharactersInRangeto limit user input for numbers:

func textField(textField: UITextField,
    shouldChangeCharactersInRange range: NSRange,
    replacementString string: String) -> Bool {

    // Create an `NSCharacterSet` set which includes everything *but* the digits
    let inverseSet = NSCharacterSet(charactersInString:"0123456789").invertedSet

    // At every character in this "inverseSet" contained in the string,
    // split the string up into components which exclude the characters
    // in this inverse set
    let components = string.componentsSeparatedByCharactersInSet(inverseSet)

    // Rejoin these components
    let filtered = components.joinWithSeparator("")  // use join("", components) if you are using Swift 1.2

    // If the original string is equal to the filtered string, i.e. if no
    // inverse characters were present to be eliminated, the input is valid
    // and the statement returns true; else it returns false
    return string == filtered
}

---

Updated for Swift 3:

 func textField(_ textField: UITextField, 
    shouldChangeCharactersIn range: NSRange, 
    replacementString string: String) -> Bool {

    // Create an `NSCharacterSet` set which includes everything *but* the digits
    let inverseSet = NSCharacterSet(charactersIn:"0123456789").inverted

    // At every character in this "inverseSet" contained in the string,
    // split the string up into components which exclude the characters
    // in this inverse set
    let components = string.components(separatedBy: inverseSet)

    // Rejoin these components
    let filtered = components.joined(separator: "")  // use join("", components) if you are using Swift 1.2

    // If the original string is equal to the filtered string, i.e. if no
    // inverse characters were present to be eliminated, the input is valid
    // and the statement returns true; else it returns false
    return string == filtered  
}

Answer 2

For those looking for a shorter answer, I found this quite useful.

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    // remove non-numerics and compare with original string
    return string == string.filter("0123456789".contains)
}

Works in Xcode 10.1, Swift 4.2

Answer 3

  -, UITextViewDelegate

class ViewController: UIViewController, UITextViewDelegate {

2- IBOutlet

@IBOutlet weak var firstName: UITextField!

3-, ,

override func viewDidLoad() {
        super.viewDidLoad()
   firstName.delegate = self
}


func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    if textField == firstName {
                let allowedCharacters = "1234567890"
                let allowedCharacterSet = CharacterSet(charactersIn: allowedCharacters)
                let typedCharacterSet = CharacterSet(charactersIn: string)
                let alphabet = allowedCharacterSet.isSuperset(of: typedCharacterSet)
                let Range = range.length + range.location > (fnameTF.text?.count)!

        if Range == false && alphabet == false {
            return false
        }


        let NewLength = (fnameTF.text?.count)! + string.count - range.length
        return NewLength <= 10


      } else {
        return false
    }
  }

Answer 4

Swift 4.1 Xcode 10

UITextFieldDelegate

class YourViewController: UIViewController, UITextFieldDelegate

viewDidLoad()

yourTF.delegate = self

//MARK - UITextField Delegates
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    //For numers
    if textField == yourTF {
        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
}

Answer 5

, iOS , . - UITextFieldDelegate, :

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

"^([0-9]+)?(\\.([0-9]{1,2})?)?$"

[NSCharacterSet decimalDigitCharacterSet]

, YES, set else return NO.

Answer 6

, .

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