Formatieren eines UITextFields für die Kreditkarteneingabe wie (xxxx xxxx xxxx xxxx)

Sie können meinen Code wahrscheinlich optimieren oder es gibt einen einfacheren Weg, aber dieser Code sollte funktionieren

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

    __block NSString *text = [textField text];

    NSCharacterSet *characterSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789\b"];
    string = [string stringByReplacingOccurrencesOfString:@" " withString:@""];
    if ([string rangeOfCharacterFromSet:[characterSet invertedSet]].location != NSNotFound) {
        return NO;
    }

    text = [text stringByReplacingCharactersInRange:range withString:string];
    text = [text stringByReplacingOccurrencesOfString:@" " withString:@""];

    NSString *newString = @"";
    while (text.length > 0) {
        NSString *subString = [text substringToIndex:MIN(text.length, 4)];
        newString = [newString stringByAppendingString:subString];
        if (subString.length == 4) {
            newString = [newString stringByAppendingString:@" "];
        }
        text = [text substringFromIndex:MIN(text.length, 4)];
    }

    newString = [newString stringByTrimmingCharactersInSet:[characterSet invertedSet]];

    if (newString.length >= 20) {
        return NO;
    }

    [textField setText:newString];

    return NO;
}

Unten ist ein funktionierender Swift 4-Port von Logicopolis's Antwort (der wiederum ein Swift 2-Port einer alten Version meiner akzeptierten Antwort ist in Objective-C) mit cnotethegr8 .__ erweitert. s Trick für die Unterstützung von Amex-Karten und dann weiter verbessert, um weitere Kartenformate zu unterstützen. Ich schlage vor, die akzeptierte Antwort zu überprüfen, falls Sie dies nicht bereits getan haben, da dies die Motivation für viele dieser Codes erklärt.

Beachten Sie, dass eine minimale Reihe von Schritten erforderlich ist, um dies in Aktion zu sehen:

1. Erstellen Sie in Swift ein neues Single View App.
2. Fügen Sie am Main.storyboard ein Textfeld hinzu.
3. Machen Sie ViewController zum Delegaten von Textfeld.
4. Fügen Sie den Code unten in ViewController.Swift ein.
5. Verbinden Sie das IBOutlet mit dem Textfeld.
6. Führen Sie Ihre App aus und geben Sie Textfeld ein.

import UIKit

class ViewController: UIViewController, UITextFieldDelegate {
    private var previousTextFieldContent: String?
    private var previousSelection: UITextRange?
    @IBOutlet var yourTextField: UITextField!;

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib
        yourTextField.addTarget(self, action: #selector(reformatAsCardNumber), for: .editingChanged)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        previousTextFieldContent = textField.text;
        previousSelection = textField.selectedTextRange;
        return true
    }

    @objc func reformatAsCardNumber(textField: UITextField) {
        var targetCursorPosition = 0
        if let startPosition = textField.selectedTextRange?.start {
            targetCursorPosition = textField.offset(from: textField.beginningOfDocument, to: startPosition)
        }

        var cardNumberWithoutSpaces = ""
        if let text = textField.text {
            cardNumberWithoutSpaces = self.removeNonDigits(string: text, andPreserveCursorPosition: &targetCursorPosition)
        }

        if cardNumberWithoutSpaces.count > 19 {
            textField.text = previousTextFieldContent
            textField.selectedTextRange = previousSelection
            return
        }

        let cardNumberWithSpaces = self.insertCreditCardSpaces(cardNumberWithoutSpaces, preserveCursorPosition: &targetCursorPosition)
        textField.text = cardNumberWithSpaces

        if let targetPosition = textField.position(from: textField.beginningOfDocument, offset: targetCursorPosition) {
            textField.selectedTextRange = textField.textRange(from: targetPosition, to: targetPosition)
        }
    }

    func removeNonDigits(string: String, andPreserveCursorPosition cursorPosition: inout Int) -> String {
        var digitsOnlyString = ""
        let originalCursorPosition = cursorPosition

        for i in Swift.stride(from: 0, to: string.count, by: 1) {
            let characterToAdd = string[string.index(string.startIndex, offsetBy: i)]
            if characterToAdd >= "0" && characterToAdd <= "9" {
                digitsOnlyString.append(characterToAdd)
            }
            else if i < originalCursorPosition {
                cursorPosition -= 1
            }
        }

        return digitsOnlyString
    }

    func insertCreditCardSpaces(_ string: String, preserveCursorPosition cursorPosition: inout Int) -> String {
        // Mapping of card prefix to pattern is taken from
        // https://baymard.com/checkout-usability/credit-card-patterns

        // UATP cards have 4-5-6 (XXXX-XXXXX-XXXXXX) format
        let is456 = string.hasPrefix("1")

        // These prefixes reliably indicate either a 4-6-5 or 4-6-4 card. We treat all these
        // as 4-6-5-4 to err on the side of always letting the user type more digits.
        let is465 = [
            // Amex
            "34", "37",

            // Diners Club
            "300", "301", "302", "303", "304", "305", "309", "36", "38", "39"
        ].contains { string.hasPrefix($0) }

        // In all other cases, assume 4-4-4-4-3.
        // This won't always be correct; for instance, Maestro has 4-4-5 cards according
        // to https://baymard.com/checkout-usability/credit-card-patterns, but I don't
        // know what prefixes identify particular formats.
        let is4444 = !(is456 || is465)

        var stringWithAddedSpaces = ""
        let cursorPositionInSpacelessString = cursorPosition

        for i in 0..<string.count {
            let needs465Spacing = (is465 && (i == 4 || i == 10 || i == 15))
            let needs456Spacing = (is456 && (i == 4 || i == 9 || i == 15))
            let needs4444Spacing = (is4444 && i > 0 && (i % 4) == 0)

            if needs465Spacing || needs456Spacing || needs4444Spacing {
                stringWithAddedSpaces.append(" ")

                if i < cursorPositionInSpacelessString {
                    cursorPosition += 1
                }
            }

            let characterToAdd = string[string.index(string.startIndex, offsetBy:i)]
            stringWithAddedSpaces.append(characterToAdd)
        }

        return stringWithAddedSpaces
    }
}

Die Anpassung an andere Situationen - beispielsweise wenn Ihr Delegierter kein ViewController ist - bleibt dem Leser als Übung überlassen.

Ich denke, das ist gut:

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

        NSLog(@"%@",NSStringFromRange(range));

        // Only the 16 digits + 3 spaces
        if (range.location == 19) {
            return NO;
        }

        // Backspace
        if ([string length] == 0)
            return YES;

        if ((range.location == 4) || (range.location == 9) || (range.location == 14))
        {

            NSString *str    = [NSString stringWithFormat:@"%@ ",textField.text];
            textField.text   = str;
        }

        return YES;
    }

Swift 3 Lösung mit Fawkes Antwort als Basis . Unterstützung für das Amex-Kartenformat . Bei Änderung des Kartentyps wurde eine Neuformulierung hinzugefügt.

Erstellen Sie zuerst eine neue Klasse mit diesem Code:

extension String {

    func containsOnlyDigits() -> Bool
    {

        let notDigits = NSCharacterSet.decimalDigits.inverted

        if rangeOfCharacter(from: notDigits, options: String.CompareOptions.literal, range: nil) == nil
        {
            return true
        }

        return false
    }
}
import UIKit

var creditCardFormatter : CreditCardFormatter
{
    return CreditCardFormatter.sharedInstance
}

class CreditCardFormatter : NSObject
{
    static let sharedInstance : CreditCardFormatter = CreditCardFormatter()

    func formatToCreditCardNumber(isAmex: Bool, textField : UITextField, withPreviousTextContent previousTextContent : String?, andPreviousCursorPosition previousCursorSelection : UITextRange?) {
        var selectedRangeStart = textField.endOfDocument
        if textField.selectedTextRange?.start != nil {
            selectedRangeStart = (textField.selectedTextRange?.start)!
        }
        if  let textFieldText = textField.text
        {
            var targetCursorPosition : UInt = UInt(textField.offset(from:textField.beginningOfDocument, to: selectedRangeStart))
            let cardNumberWithoutSpaces : String = removeNonDigitsFromString(string: textFieldText, andPreserveCursorPosition: &targetCursorPosition)
            if cardNumberWithoutSpaces.characters.count > 19
            {
                textField.text = previousTextContent
                textField.selectedTextRange = previousCursorSelection
                return
            }
            var cardNumberWithSpaces = ""
            if isAmex {
                cardNumberWithSpaces = insertSpacesInAmexFormat(string: cardNumberWithoutSpaces, andPreserveCursorPosition: &targetCursorPosition)
            }
            else
            {
                cardNumberWithSpaces = insertSpacesIntoEvery4DigitsIntoString(string: cardNumberWithoutSpaces, andPreserveCursorPosition: &targetCursorPosition)
            }
            textField.text = cardNumberWithSpaces
            if let finalCursorPosition = textField.position(from:textField.beginningOfDocument, offset: Int(targetCursorPosition))
            {
                textField.selectedTextRange = textField.textRange(from: finalCursorPosition, to: finalCursorPosition)
            }
        }
    }

    func removeNonDigitsFromString(string : String, andPreserveCursorPosition cursorPosition : inout UInt) -> String {
        var digitsOnlyString : String = ""
        for index in stride(from: 0, to: string.characters.count, by: 1)
        {
            let charToAdd : Character = Array(string.characters)[index]
            if isDigit(character: charToAdd)
            {
                digitsOnlyString.append(charToAdd)
            }
            else
            {
                if index < Int(cursorPosition)
                {
                    cursorPosition -= 1
                }
            }
        }
        return digitsOnlyString
    }

    private func isDigit(character : Character) -> Bool
    {
        return "\(character)".containsOnlyDigits()
    }

    func insertSpacesInAmexFormat(string : String, andPreserveCursorPosition cursorPosition : inout UInt) -> String {
        var stringWithAddedSpaces : String = ""
        for index in stride(from: 0, to: string.characters.count, by: 1)
        {
            if index == 4
            {
                stringWithAddedSpaces += " "
                if index < Int(cursorPosition)
                {
                    cursorPosition += 1
                }
            }
            if index == 10 {
                stringWithAddedSpaces += " "
                if index < Int(cursorPosition)
                {
                    cursorPosition += 1
                }
            }
            if index < 15 {
               let characterToAdd : Character = Array(string.characters)[index]
                stringWithAddedSpaces.append(characterToAdd)
            }
        }
        return stringWithAddedSpaces
    }


    func insertSpacesIntoEvery4DigitsIntoString(string : String, andPreserveCursorPosition cursorPosition : inout UInt) -> String {
        var stringWithAddedSpaces : String = ""
        for index in stride(from: 0, to: string.characters.count, by: 1)
        {
            if index != 0 && index % 4 == 0 && index < 16
            {
                stringWithAddedSpaces += " "

                if index < Int(cursorPosition)
                {
                    cursorPosition += 1
                }
            }
            if index < 16 {
                let characterToAdd : Character = Array(string.characters)[index]
                stringWithAddedSpaces.append(characterToAdd)
            }
        }
        return stringWithAddedSpaces
    }

}

Fügen Sie in Ihrer ViewControllerClass diese Funktion hinzu

func reformatAsCardNumber(textField:UITextField){
  let formatter = CreditCardFormatter()
  var isAmex = false
  if selectedCardType == "AMEX" {
    isAmex = true
    }
  formatter.formatToCreditCardNumber(isAmex: isAmex, textField: textField, withPreviousTextContent: textField.text, andPreviousCursorPosition: textField.selectedTextRange)
}

Fügen Sie dann Ihrem textField ein Ziel hinzu

youtTextField.addTarget(self, action: #selector(self.reformatAsCardNumber(textField:)), for: UIControlEvents.editingChanged)

Registrieren Sie die neue Variable und senden Sie den Kartentyp

var selectedCardType: String? {
  didSet{
    reformatAsCardNumber(textField: yourTextField)
  }
}

Danke Fawkes für seinen Code!

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool
    {
        if textField == CardNumTxt
        {
            let replacementStringIsLegal = string.rangeOfCharacterFromSet(NSCharacterSet(charactersInString: "0123456789").invertedSet) == nil

            if !replacementStringIsLegal
            {
                return false
            }

            let newString = (textField.text! as NSString).stringByReplacingCharactersInRange(range, withString: string)
            let components = newString.componentsSeparatedByCharactersInSet(NSCharacterSet(charactersInString: "0123456789").invertedSet)

            let decimalString = components.joinWithSeparator("") as NSString
            let length = decimalString.length
            let hasLeadingOne = length > 0 && decimalString.characterAtIndex(0) == (1 as unichar)

            if length == 0 || (length > 16 && !hasLeadingOne) || length > 19
            {
                let newLength = (textField.text! as NSString).length + (string as NSString).length - range.length as Int

                return (newLength > 16) ? false : true
            }
            var index = 0 as Int
            let formattedString = NSMutableString()

            if hasLeadingOne
            {
                formattedString.appendString("1 ")
                index += 1
            }
            if length - index > 4
            {
                let prefix = decimalString.substringWithRange(NSMakeRange(index, 4))
                formattedString.appendFormat("%@-", prefix)
                index += 4
            }

            if length - index > 4
            {
                let prefix = decimalString.substringWithRange(NSMakeRange(index, 4))
                formattedString.appendFormat("%@-", prefix)
                index += 4
            }
            if length - index > 4
            {
                let prefix = decimalString.substringWithRange(NSMakeRange(index, 4))
                formattedString.appendFormat("%@-", prefix)
                index += 4
            }


            let remainder = decimalString.substringFromIndex(index)
            formattedString.appendString(remainder)
            textField.text = formattedString as String
            return false
        }
        else
        {
            return true
        }
    }

formatted String.appendFormat ("% @ -", Präfix) Änderung von "-" beliebiger anderer Optionen

Noch eine Version der akzeptierten Antwort in Swift 2 ...

Stellen Sie sicher, dass Sie diese in Ihrer Delegierteninstanz haben:

private var previousTextFieldContent: String?
private var previousSelection: UITextRange?

Stellen Sie außerdem sicher, dass Ihr Textfeld reformatAsCardNumber aufruft:

textField.addTarget(self, action: #selector(reformatAsCardNumber(_:)), forControlEvents: .EditingChanged)

Ihr Textfelddelegierter muss dies tun:

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    previousTextFieldContent = textField.text;
    previousSelection = textField.selectedTextRange;
    return true
}

Fügen Sie schließlich die folgenden Methoden hinzu:

func reformatAsCardNumber(textField: UITextField) {
    var targetCursorPosition = 0
    if let startPosition = textField.selectedTextRange?.start {
        targetCursorPosition = textField.offsetFromPosition(textField.beginningOfDocument, toPosition: startPosition)
    }

    var cardNumberWithoutSpaces = ""
    if let text = textField.text {
        cardNumberWithoutSpaces = self.removeNonDigits(text, andPreserveCursorPosition: &targetCursorPosition)
    }

    if cardNumberWithoutSpaces.characters.count > 19 {
        textField.text = previousTextFieldContent
        textField.selectedTextRange = previousSelection
        return
    }

    let cardNumberWithSpaces = self.insertSpacesEveryFourDigitsIntoString(cardNumberWithoutSpaces, andPreserveCursorPosition: &targetCursorPosition)
    textField.text = cardNumberWithSpaces

    if let targetPosition = textField.positionFromPosition(textField.beginningOfDocument, offset: targetCursorPosition) {
        textField.selectedTextRange = textField.textRangeFromPosition(targetPosition, toPosition: targetPosition)
    }
}

func removeNonDigits(string: String, inout andPreserveCursorPosition cursorPosition: Int) -> String {
    var digitsOnlyString = ""
    let originalCursorPosition = cursorPosition

    for i in 0.stride(to: string.characters.count, by: 1) {
        let characterToAdd = string[string.startIndex.advancedBy(i)]
        if characterToAdd >= "0" && characterToAdd <= "9" {
            digitsOnlyString.append(characterToAdd)
        }
        else if i < originalCursorPosition {
            cursorPosition -= 1
        }
    }

    return digitsOnlyString
}

func insertSpacesEveryFourDigitsIntoString(string: String, inout andPreserveCursorPosition cursorPosition: Int) -> String {
    var stringWithAddedSpaces = ""
    let cursorPositionInSpacelessString = cursorPosition

    for i in 0.stride(to: string.characters.count, by: 1) {
        if i > 0 && (i % 4) == 0 {
            stringWithAddedSpaces.appendContentsOf(" ")
            if i < cursorPositionInSpacelessString {
                cursorPosition += 1
            }
        }
        let characterToAdd = string[string.startIndex.advancedBy(i)]
        stringWithAddedSpaces.append(characterToAdd)
    }

    return stringWithAddedSpaces
}

Hier ist eine Swift-Version für den Fall, dass dies für alle nützlich ist, die noch nach dieser Antwort suchen, jedoch Swift anstelle von Objective-C verwenden. Die Konzepte sind trotzdem gleich.

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool
{
    //range.length will be greater than 0 if user is deleting text - allow it to replace
    if range.length > 0
    {
        return true
    }

    //Don't allow empty strings
    if string == " "
    {
        return false
    }

    //Check for max length including the spacers we added
    if range.location == 20
    {
        return false
    }

    var originalText = textField.text
    let replacementText = string.stringByReplacingOccurrencesOfString(" ", withString: "")

    //Verify entered text is a numeric value
    let digits = NSCharacterSet.decimalDigitCharacterSet()
    for char in replacementText.unicodeScalars
    {
        if !digits.longCharacterIsMember(char.value)
        {
            return false
        }
    }

    //Put an empty space after every 4 places
    if originalText!.length() % 5 == 0
    {
        originalText?.appendContentsOf(" ")
        textField.text = originalText
    }

    return true
}

Definieren Sie die Methode unten und rufen Sie sie in UITextfield-Delegierten oder wo immer erforderlich auf

-(NSString*)processString :(NSString*)yourString
{
    if(yourString == nil){
        return @"";
    }
    int stringLength = (int)[yourString length];
    int len = 4;  // Length after which you need to place added character
    NSMutableString *str = [NSMutableString string];
    int i = 0;
    for (; i < stringLength; i+=len) {
        NSRange range = NSMakeRange(i, len);
        [str appendString:[yourString substringWithRange:range]];
        if(i!=stringLength -4){
            [str appendString:@" "]; //If required string format is XXXX-XXXX-XXXX-XXX then just replace [str appendString:@"-"]
        }
    }
    if (i < [str length]-1) {  // add remaining part
        [str appendString:[yourString substringFromIndex:i]];
    }
    //Returning required string

    return str;
}

Also wollte ich dies mit weniger Code, also habe ich den Code hier verwendet und ihn ein wenig anders umgesetzt. Ich hatte zwei Felder auf dem Bildschirm, eines für die Nummer und eines für das Verfallsdatum, sodass ich es wiederverwendbar machte. 

Swift 3 alternative Antwort

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    guard let currentText = (textField.text as NSString?)?.replacingCharacters(in: range, with: string) else { return true }

    if textField == cardNumberTextField {
        textField.text = currentText.grouping(every: 4, with: " ")
        return false
    }
    else { // Expiry Date Text Field
        textField.text = currentText.grouping(every: 2, with: "/")
        return false
    }
}

extension String {
    func grouping(every groupSize: String.IndexDistance, with separator: Character) -> String {
       let cleanedUpCopy = replacingOccurrences(of: String(separator), with: "")
       return String(cleanedUpCopy.characters.enumerated().map() {
            $0.offset % groupSize == 0 ? [separator, $0.element] : [$0.element]
       }.joined().dropFirst())
    }
}

Um das Ziel zu erreichen, den in das Textfeld eingegebenen Text auf diese Weise zu formatieren, ist es wichtig, einige wichtige Dinge zu beachten XXXX XXXX XXXX XXXX XXXX. Neben der Tatsache, dass die 16-stellige Kartennummer, die alle vier Ziffern getrennt ist, das am häufigsten verwendete Format ist, gibt es Karten mit 15 Ziffern (AmEx-Format XXXX XXXXXX XXXXX) und andere mit 13 Ziffern oder sogar 19 Ziffern ( https://en.wikipedia.org/wiki/Payment_card_number ). Eine weitere wichtige Sache, die Sie berücksichtigen sollten, ist, textField so zu konfigurieren, dass nur Ziffern zulässig sind. Konfigurieren Sie den Tastaturtyp, da numberPad ein guter Anfang ist, aber es ist praktisch, eine Methode zu implementieren, die die Eingabe sicherstellt.

Ein Ausgangspunkt ist, zu entscheiden, wann Sie die Nummer formatieren möchten, während der Benutzer die Nummer eingibt Oder wenn der Benutzer das Textfeld verlässt . Falls Sie formatieren möchten, wenn der Benutzer das Textfeld verlässt Praktisch für Verwenden Sie die Delegierte-Methode textFieldDidEndEditing (_ :), nehmen Sie den Inhalt des textField und formatieren Sie ihn. 

In dem Fall, in dem der Benutzer die Nummer eingibt, ist die Delegat-Methode TextField (_: shouldChangeCharactersIn: replacementString :) nützlich, die Aufgerufen wird, wenn sich der aktuelle Text ändert.

In beiden Fällen gibt es immer noch ein Problem. Finden Sie heraus, welches das richtige Format für die eingegebene Nummer ist, IMHO. Basierend auf allen Zahlen, die ich gesehen habe, gibt es nur zwei Hauptformate: das Amex-Format mit 15 oben beschriebenen Ziffern und das Formatieren Sie die Gruppenkartennummer alle vier Ziffern, wobei es sich nicht um die Anzahl der Ziffern handelt, da es sich hierbei um eine generische Regel handelt. Beispiel: Eine Karte mit 13 Ziffern wird formatiert. XXXXX XXXX XXXX X und mit 19 Ziffern wird dieser XXXX angezeigt XXXX XXXX XXXX XXX, dies funktioniert in den meisten Fällen (16 Ziffern) und auch in den anderen Fällen. So können Sie herausfinden, wie Sie den AmEx-Fall mit demselben Algorithmus verwalten, der mit den magischen Zahlen spielt.

Ich habe einen RegEx verwendet, um sicherzustellen, dass eine 15-stellige Karte eine American Express-Karte ist, im Fall anderer Formate 

let regex = NSPredicate(format: "SELF MATCHES %@", "3[47][A-Za-z0-9*-]{13,}" )
let isAmex = regex.evaluate(with: stringToValidate)

Ich empfehle dringend, das spezifische RegEx zu verwenden, das nützlich ist, um den Emittenten zu identifizieren und um herauszufinden, wie viele Ziffern akzeptiert werden sollten.

Nun ist mein schneller Ansatz der Lösung mit textFieldDidEndEditing 

func textFieldDidEndEditing(_ textField: UITextField) {

    _=format(cardNumber: textField.text!)

}
func format(cardNumber:String)->String{
    var formatedCardNumber = ""
    var i :Int = 0
    //loop for every character
    for character in cardNumber.characters{
        //in case you want to replace some digits in the middle with * for security
        if(i < 6 || i >= cardNumber.characters.count - 4){
            formatedCardNumber = formatedCardNumber + String(character)
        }else{
            formatedCardNumber = formatedCardNumber + "*"
        }
        //insert separators every 4 spaces(magic number)
        if(i == 3 || i == 7 || i == 11 || (i == 15 && cardNumber.characters.count > 16 )){
            formatedCardNumber = formatedCardNumber + "-"
            // could use just " " for spaces
        }

        i = i + 1
    }
    return formatedCardNumber
}

und für shouldChangeCharactersIn: replacementString: ein Swift 3.0 Von Jayesh Miruliya Answer wird ein Trennzeichen zwischen der Gruppe von vier Zeichen eingefügt

 func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool
    {
        if textField == CardNumTxt
        {
            let replacementStringIsLegal = string.rangeOfCharacter(from: CharacterSet(charactersIn: "0123456789").inverted) == nil

        if !replacementStringIsLegal
        {
            return false
        }

        let newString = (textField.text! as NSString).replacingCharacters(in: range, with: string)
        let components = newString.components(separatedBy: CharacterSet(charactersIn: "0123456789").inverted)

        let decimalString = components.joined(separator: "") as NSString
        let length = decimalString.length
        let hasLeadingOne = length > 0 && decimalString.character(at: 0) == (1 as unichar)

        if length == 0 || (length > 16 && !hasLeadingOne) || length > 19
        {
            let newLength = (textField.text! as NSString).length + (string as NSString).length - range.length as Int

            return (newLength > 16) ? false : true
        }
        var index = 0 as Int
        let formattedString = NSMutableString()

        if hasLeadingOne
        {
            formattedString.append("1 ")
            index += 1
        }
        if length - index > 4 //magic number separata every four characters
        {
            let prefix = decimalString.substring(with: NSMakeRange(index, 4))
            formattedString.appendFormat("%@-", prefix)
            index += 4
        }

        if length - index > 4
        {
            let prefix = decimalString.substring(with: NSMakeRange(index, 4))
            formattedString.appendFormat("%@-", prefix)
            index += 4
        }
        if length - index > 4
        {
            let prefix = decimalString.substring(with: NSMakeRange(index, 4))
            formattedString.appendFormat("%@-", prefix)
            index += 4
        }


        let remainder = decimalString.substring(from: index)
        formattedString.append(remainder)
        textField.text = formattedString as String
        return false
        }
        else
        {
            return true
        }
    }

Swift 3.2

Kleine Korrektur in @Lucas Antwort und Arbeitscode in Swift 3.2. Das Leerzeichen wird automatisch entfernt.

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

    if range.location == 19 {
        return false
    }

    if range.length == 1 {
        if (range.location == 5 || range.location == 10 || range.location == 15) {
            let text = textField.text ?? ""
            textField.text = text.substring(to: text.index(before: text.endIndex))
        }
        return true
    }

    if (range.location == 4 || range.location == 9 || range.location == 14) {
        textField.text = String(format: "%@ ", textField.text ?? "")
    }

    return true
}

Swift 5, Xcode 10.3

Nachdem ich viele Lösungen ausprobiert hatte, hatte ich Probleme wie das Einstellen der korrekten Cursorposition und das Formatieren nach Bedarf. Nach dem Kombinieren von zwei Beiträgen fand ich schließlich eine Lösung ( https://stackoverflow.com/a/38838740/10579134 , https://stackoverflow.com/a/45297778/10579134 )

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    guard let currentText = (textField.text as NSString?)?.replacingCharacters(in: range, with: string) else { return true }


    if textField == yourTextField  {

        textField.setText(to: currentText.grouping(every: 4, with: "-"), preservingCursor: true)

        return false
    }
    return true
}

Und diese Erweiterung hinzufügen

extension UITextField {

public func setText(to newText: String, preservingCursor: Bool) {
    if preservingCursor {
        let cursorPosition = offset(from: beginningOfDocument, to: selectedTextRange!.start) + newText.count - (text?.count ?? 0)
        text = newText
        if let newPosition = self.position(from: beginningOfDocument, offset: cursorPosition) {
            selectedTextRange = textRange(from: newPosition, to: newPosition)
        }
    }
    else {
        text = newText
    }
}

Hier ist eine schnelle Kopie der akzeptierten Antwort für den Fall, dass jemand sie benötigt. Es ist im Grunde eine Wrapper-Klasse. Ich habe nicht viel Zeit damit verbracht, es zu optimieren, aber es ist einsatzbereit.

var creditCardFormatter : CreditCardFormatter
{
    return CreditCardFormatter.sharedInstance
}

class CreditCardFormatter : NSObject
{
    static let sharedInstance : CreditCardFormatter = CreditCardFormatter()

    func formatToCreditCardNumber(textField : UITextField, withPreviousTextContent previousTextContent : String?, andPreviousCursorPosition previousCursorSelection : UITextRange?)
    {
        if let selectedRangeStart = textField.selectedTextRange?.start, textFieldText = textField.text
        {
            var targetCursorPosition : UInt = UInt(textField.offsetFromPosition(textField.beginningOfDocument, toPosition: selectedRangeStart))

            let cardNumberWithoutSpaces : String = removeNonDigitsFromString(textFieldText, andPreserveCursorPosition: &targetCursorPosition)

            if cardNumberWithoutSpaces.characters.count > 19
            {
                textField.text = previousTextContent
                textField.selectedTextRange = previousCursorSelection
                return
            }

            let cardNumberWithSpaces : String = insertSpacesIntoEvery4DigitsIntoString(cardNumberWithoutSpaces, andPreserveCursorPosition: &targetCursorPosition)

            textField.text = cardNumberWithSpaces

            if let finalCursorPosition = textField.positionFromPosition(textField.beginningOfDocument, offset: Int(targetCursorPosition))
            {
                textField.selectedTextRange = textField.textRangeFromPosition(finalCursorPosition, toPosition: finalCursorPosition)
            }
        }
    }

    func removeNonDigitsFromString(string : String,inout andPreserveCursorPosition cursorPosition : UInt) -> String
    {
        var digitsOnlyString : String = ""

        for index in 0.stride(to: string.characters.count, by: 1)
        {
            let charToAdd : Character = Array(string.characters)[index]

            if isDigit(charToAdd)
            {
                digitsOnlyString.append(charToAdd)
            }
            else
            {
                if index < Int(cursorPosition)
                {
                    cursorPosition -= 1
                }
            }
        }

        return digitsOnlyString
    }

    private func isDigit(character : Character) -> Bool
    {
        return "\(character)".containsOnlyDigits()
    }

    func insertSpacesIntoEvery4DigitsIntoString(string : String, inout andPreserveCursorPosition cursorPosition : UInt) -> String
    {
        var stringWithAddedSpaces : String = ""

        for index in 0.stride(to: string.characters.count, by: 1)
        {
            if index != 0 && index % 4 == 0
            {
                stringWithAddedSpaces += " "

                if index < Int(cursorPosition)
                {
                    cursorPosition += 1
                }
            }

            let characterToAdd : Character = Array(string.characters)[index]

            stringWithAddedSpaces.append(characterToAdd)
        }

        return stringWithAddedSpaces
    }

}

extension String
{
    func containsOnlyDigits() -> Bool
    {
        let notDigits : NSCharacterSet = NSCharacterSet.decimalDigitCharacterSet().invertedSet

        if (rangeOfCharacterFromSet(notDigits, options: NSStringCompareOptions.LiteralSearch, range: nil) == nil)
        {
            return true
        }

        return false
    }
}

Swift 3-Lösung basierend auf Mark Amerys Objective-C-Lösung :

1. Implementieren Sie Maßnahmen und delegieren Sie Methoden:

   textField.addTarget(self, action: #selector(reformatAsCardNumber(_:))
   textField.delegate = self
   

2. TextField Delegate-Methoden und andere Methoden:

   func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
       previousTextFieldContent = textField.text;
       previousSelection = textField.selectedTextRange;
       return true
   }
   
   func reformatAsCardNumber(_ textField: UITextField) {
       var targetCursorPosition = 0
       if let startPosition = textField.selectedTextRange?.start {
           targetCursorPosition = textField.offset(from:textField.beginningOfDocument, to: startPosition)
       }
   
       var cardNumberWithoutSpaces = ""
       if let text = textField.text {
           cardNumberWithoutSpaces = removeNonDigits(string: text, andPreserveCursorPosition: &targetCursorPosition)
       }
   
       if cardNumberWithoutSpaces.characters.count > 19 {
           textField.text = previousTextFieldContent
           textField.selectedTextRange = previousSelection
           return
       }
   
       let cardNumberWithSpaces = self.insertSpacesEveryFourDigitsIntoString(string: cardNumberWithoutSpaces, andPreserveCursorPosition: &targetCursorPosition)
       textField.text = cardNumberWithSpaces
   
       if let targetPosition = textField.position(from: textField.beginningOfDocument, offset: targetCursorPosition) {
           textField.selectedTextRange = textField.textRange(from: targetPosition, to: targetPosition)
       }
   }
   
   func removeNonDigits(string: String, andPreserveCursorPosition cursorPosition: inout Int) -> String {
       var digitsOnlyString = ""
       let originalCursorPosition = cursorPosition
   
       for i in stride(from: 0, to: string.characters.count, by: 1) {
           let characterToAdd =  string[string.index(string.startIndex, offsetBy: i)]
           if characterToAdd >= "0" && characterToAdd <= "9" {
               digitsOnlyString.append(characterToAdd)
           }
           else if i < originalCursorPosition {
               cursorPosition -= 1
           }
       }
   
       return digitsOnlyString
   }
   
   func insertSpacesEveryFourDigitsIntoString(string: String, andPreserveCursorPosition cursorPosition: inout Int) -> String {
       var stringWithAddedSpaces = ""
       let cursorPositionInSpacelessString = cursorPosition
   
       for i in stride(from: 0, to: string.characters.count, by: 1) {
           if i > 0 && (i % 4) == 0 {
               stringWithAddedSpaces.append(" ")
               if i < cursorPositionInSpacelessString {
                   cursorPosition += 1
               }
           }
           let characterToAdd = string[string.index(string.startIndex, offsetBy: i)]
           stringWithAddedSpaces.append(characterToAdd)
       }
   
       return stringWithAddedSpaces
   }
   

ich habe @ilesh answer so modifiziert, dass nur die letzten 4 Ziffern angezeigt werden, unabhängig von der Länge. Um auch das Leerzeichen und die Zeichen "-" zu ignorieren . Wenn wir eine Zahl mit dem Format 0000 - 0000 - 0000 - 0000 haben, wird XXXX - XXXX - XXXX - 0000 angezeigt

func setStringAsCardNumberWithSartNumber(Number:Int,withString str:String) -> String{
    let arr = str.characters
    var CrediteCard : String = ""
    let len = str.characters.count-4
    if arr.count > (Number + len) {
        for (index, element ) in arr.enumerated(){
            if index >= Number && index < (Number + len) && element != "-" && element != " " {
                CrediteCard = CrediteCard + String("X")
            }else{
                CrediteCard = CrediteCard + String(element)
            }
        }
        return CrediteCard
    }else{
        print("\(Number) plus \(len) are grether than strings chatarter \(arr.count)")
    }
    print("\(CrediteCard)")
    return str
}

Erstellen Sie eine neue Swift-Datei und fügen Sie den folgenden Code ein. Ändern Sie die Textfeldklasse in VSTextField 

import UIKit

public enum TextFieldFormatting {
    case uuid
    case socialSecurityNumber
    case phoneNumber
    case custom
    case noFormatting
}

public class VSTextField: UITextField {

    /**
     Set a formatting pattern for a number and define a replacement string. For example: If formattingPattern would be "##-##-AB-##" and
     replacement string would be "#" and user input would be "123456", final string would look like "12-34-AB-56"
     */
    public func setFormatting(_ formattingPattern: String, replacementChar: Character) {
        self.formattingPattern = formattingPattern
        self.replacementChar = replacementChar
        self.formatting = .custom
    }

    /**
     A character which will be replaced in formattingPattern by a number
     */
    public var replacementChar: Character = "*"

    /**
     A character which will be replaced in formattingPattern by a number
     */
    public var secureTextReplacementChar: Character = "\u{25cf}"

    /**
     True if input number is hexadecimal eg. UUID
     */
    public var isHexadecimal: Bool {
        return formatting == .uuid
    }

    /**
     Max length of input string. You don't have to set this if you set formattingPattern.
     If 0 -> no limit.
     */
    public var maxLength = 0

    /**
     Type of predefined text formatting. (You don't have to set this. It's more a future feature)
     */
    public var formatting : TextFieldFormatting = .noFormatting {
        didSet {
            switch formatting {

            case .socialSecurityNumber:
                self.formattingPattern = "***-**-****"
                self.replacementChar = "*"

            case .phoneNumber:
                self.formattingPattern = "***-***-****"
                self.replacementChar = "*"

            case .uuid:
                self.formattingPattern = "********-****-****-****-************"
                self.replacementChar = "*"

            default:
                self.maxLength = 0
            }
        }
    }

    /**
     String with formatting pattern for the text field.
     */
    public var formattingPattern: String = "" {
        didSet {
            self.maxLength = formattingPattern.count
        }
    }

    /**
     Provides secure text entry but KEEPS formatting. All digits are replaced with the bullet character \u{25cf} .
     */
    public var formatedSecureTextEntry: Bool {
        set {
            _formatedSecureTextEntry = newValue
            super.isSecureTextEntry = false
        }

        get {
            return _formatedSecureTextEntry
        }
    }

    override public var text: String! {
        set {
            super.text = newValue
            textDidChange() // format string properly even when it's set programatically
        }

        get {
            if case .noFormatting = formatting {
                return super.text
            } else {
                // Because the UIControl target action is called before NSNotificaion (from which we fire our custom formatting), we need to
                // force update finalStringWithoutFormatting to get the latest text. Otherwise, the last character would be missing.
                textDidChange()
                return finalStringWithoutFormatting
            }
        }
    }

    required public init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        registerForNotifications()
    }

    override init(frame: CGRect) {
        super.init(frame: frame)
        registerForNotifications()
    }

    deinit {
        NotificationCenter.default.removeObserver(self)
    }

    /**
     Final text without formatting characters (read-only)
     */
    public var finalStringWithoutFormatting : String {
        return _textWithoutSecureBullets.keepOnlyDigits(isHexadecimal: isHexadecimal)
    }

    // MARK: - INTERNAL
    fileprivate var _formatedSecureTextEntry = false

    // if secureTextEntry is false, this value is similar to self.text
    // if secureTextEntry is true, you can find final formatted text without bullets here
    fileprivate var _textWithoutSecureBullets = ""

    fileprivate func registerForNotifications() {
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(VSTextField.textDidChange),
                                               name: NSNotification.Name(rawValue: "UITextFieldTextDidChangeNotification"),
                                               object: self)
    }

    @objc public func textDidChange() {
        var superText: String { return super.text ?? "" }

        // TODO: - Isn't there more elegant way how to do this?
        let currentTextForFormatting: String

        if superText.count > _textWithoutSecureBullets.count {
            currentTextForFormatting = _textWithoutSecureBullets + superText[superText.index(superText.startIndex, offsetBy: _textWithoutSecureBullets.count)...]
        } else if superText.count == 0 {
            _textWithoutSecureBullets = ""
            currentTextForFormatting = ""
        } else {
            currentTextForFormatting = String(_textWithoutSecureBullets[..<_textWithoutSecureBullets.index(_textWithoutSecureBullets.startIndex, offsetBy: superText.count)])
        }

        if formatting != .noFormatting && currentTextForFormatting.count > 0 && formattingPattern.count > 0 {
            let tempString = currentTextForFormatting.keepOnlyDigits(isHexadecimal: isHexadecimal)

            var finalText = ""
            var finalSecureText = ""

            var stop = false

            var formatterIndex = formattingPattern.startIndex
            var tempIndex = tempString.startIndex

            while !stop {
                let formattingPatternRange = formatterIndex ..< formattingPattern.index(formatterIndex, offsetBy: 1)
                if formattingPattern[formattingPatternRange] != String(replacementChar) {

                    finalText = finalText + formattingPattern[formattingPatternRange]
                    finalSecureText = finalSecureText + formattingPattern[formattingPatternRange]

                } else if tempString.count > 0 {

                    let pureStringRange = tempIndex ..< tempString.index(tempIndex, offsetBy: 1)

                    finalText = finalText + tempString[pureStringRange]

                    // we want the last number to be visible
                    if tempString.index(tempIndex, offsetBy: 1) == tempString.endIndex {
                        finalSecureText = finalSecureText + tempString[pureStringRange]
                    } else {
                        finalSecureText = finalSecureText + String(secureTextReplacementChar)
                    }

                    tempIndex = tempString.index(after: tempIndex)
                }

                formatterIndex = formattingPattern.index(after: formatterIndex)

                if formatterIndex >= formattingPattern.endIndex || tempIndex >= tempString.endIndex {
                    stop = true
                }
            }

            _textWithoutSecureBullets = finalText

            let newText = _formatedSecureTextEntry ? finalSecureText : finalText
            if newText != superText {
                super.text = _formatedSecureTextEntry ? finalSecureText : finalText
            }
        }

        // Let's check if we have additional max length restrictions
        if maxLength > 0 {
            if superText.count > maxLength {
                super.text = String(superText[..<superText.index(superText.startIndex, offsetBy: maxLength)])
                _textWithoutSecureBullets = String(_textWithoutSecureBullets[..<_textWithoutSecureBullets.index(_textWithoutSecureBullets.startIndex, offsetBy: maxLength)])
            }
        }
    }
}


extension String {

    func keepOnlyDigits(isHexadecimal: Bool) -> String {
        let ucString = self.uppercased()
        let validCharacters = isHexadecimal ? "0123456789ABCDEF" : "0123456789"
        let characterSet: CharacterSet = CharacterSet(charactersIn: validCharacters)
        let stringArray = ucString.components(separatedBy: characterSet.inverted)
        let allNumbers = stringArray.joined(separator: "")
        return allNumbers
    }
}


// Helpers
fileprivate func < <T: Comparable>(lhs: T?, rhs: T?) -> Bool {
    switch (lhs, rhs) {
    case let (l?, r?):
        return l < r
    case (nil, _?):
        return true
    default:
        return false
    }
}

fileprivate func > <T: Comparable>(lhs: T?, rhs: T?) -> Bool {
    switch (lhs, rhs) {
    case let (l?, r?):
        return l > r
    default:
        return rhs < lhs
    }
}

Weitere Anwendungen finden Sie unter dem Link

Danke an den Mann, der die großartige Lösung für die Formatierung von Text in UITextField zur Verfügung gestellt hat.

http://vojtastavik.com/2015/03/29/real-time-formatting-in-uitextfield-Swift-basics/

https://github.com/VojtaStavik/VSTextField

Ich arbeite großartig für mich.

Hier ist eine Antwort von Kotlin, die auf Mark Amery basiert

fun formatCardNumber(cardNumber: String): String {
    var trimmedCardNumber = cardNumber.replace(" ","")

    // UATP cards have 4-5-6 (XXXX-XXXXX-XXXXXX) format
    val is456 = trimmedCardNumber.startsWith("1")

    // These prefixes reliably indicate either a 4-6-5 or 4-6-4 card. We treat all these
    // as 4-6-5-4 to err on the side of always letting the user type more digits.
    val is465 = listOf("34", "37", "300", "301", "302", "303", "304", "305", "309", "36", "38", "39")
            .any { trimmedCardNumber.startsWith(it) }

    // In all other cases, assume 4-4-4-4.
    val is4444 = !(is456 || is465)

    trimmedCardNumber = if (is456 || is465) {
         trimmedCardNumber.take(cardNumberMaxLengthAmex)
    } else {
         trimmedCardNumber.take(cardNumberMaxLength)
    }

    var cardNumberWithAddedSpaces = ""

    trimmedCardNumber.forEachIndexed { index, c ->
        val needs465Spacing = is465 && (index == 4 || index == 10 || index == 15)
        val needs456Spacing = is456 && (index == 4 || index == 9 || index == 15)
        val needs4444Spacing = is4444 && index > 0 && index % 4 == 0

        if (needs465Spacing || needs456Spacing || needs4444Spacing) {
            cardNumberWithAddedSpaces += " "
        }

        cardNumberWithAddedSpaces += c
    }

    return cardNumberWithAddedSpaces
}

Fügen Sie dann einen Text-Listener für einen Bearbeitungstext hinzu

var flag = false

editText.addTextChangedListener(object : TextWatcher {
        override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {}

        override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
            if (flag) { 
                flag = false 
            } else {
                val text = formatCardNumber(s.toString())
                flag = true
                editText.setText(text)
                editText.setSelection(text.count())
            }
        }

        override fun afterTextChanged(s: Editable?) {}
    })

Überprüfen Sie diese Lösung. Ich habe in Autorize.net SDK Example gefunden.

Stellen Sie Ihren UITextField-Tastaturtyp auf Numeric.

Es maskiert Kreditkartennummern mit 'X' und durch das Hinzufügen von Leerzeichen wird es 'XXXX XXXX XXXX 1234'-Format.

In der Header-H-Datei

    #define kSpace @" "
    #define kCreditCardLength 16
    #define kCreditCardLengthPlusSpaces (kCreditCardLength + 3)
    #define kCreditCardObscureLength (kCreditCardLength - 4)

    @property (nonatomic, strong) NSString *creditCardBuf;
    IBOutlet UITextField *txtCardNumber;

In .m-Datei

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    if (textField == txtCardNumber) {
        if ([string length] > 0) { //NOT A BACK SPACE Add it

            if ([self isMaxLength:textField])
                return NO;

            self.creditCardBuf  = [NSString stringWithFormat:@"%@%@", self.creditCardBuf, string];
        } else {

            //Back Space do manual backspace
            if ([self.creditCardBuf length] > 1) {
                self.creditCardBuf = [self.creditCardBuf substringWithRange:NSMakeRange(0, [self.creditCardBuf length] - 1)];
            } else {
                self.creditCardBuf = @"";
            }
        }
        [self formatValue:textField];
    }

    return NO;
}

- (BOOL) isMaxLength:(UITextField *)textField {

    if (textField == txtCardNumber && [textField.text length] >= kCreditCardLengthPlusSpaces) {
        return YES;
    }
    return NO;
}

- (void) formatValue:(UITextField *)textField {
    NSMutableString *value = [NSMutableString string];

    if (textField == txtCardNumber) {
        NSInteger length = [self.creditCardBuf length];

        for (int i = 0; i < length; i++) {

            // Reveal only the last character.
            if (length <= kCreditCardObscureLength) {

                if (i == (length - 1)) {
                    [value appendString:[self.creditCardBuf substringWithRange:NSMakeRange(i,1)]];
                } else {
                    [value appendString:@“X”];
                }
            }
            // Reveal the last 4 characters
            else {

                if (i < kCreditCardObscureLength) {
                    [value appendString:@“X”];
                } else {
                    [value appendString:[self.creditCardBuf substringWithRange:NSMakeRange(i,1)]];
                }
            }

            //After 4 characters add a space
            if ((i +1) % 4 == 0 &&
                ([value length] < kCreditCardLengthPlusSpaces)) {
                [value appendString:kSpace];
            }
        }
        textField.text = value;
    }
}

Ich habe in Github einen Gist gefunden, der genau das tut, was ich in Swift3 brauche ( https://Gist.github.com/nunogoncalves/6a8b4b21f4f69e0fc050190df96a1e56 )

Implementiert von doing -> 

if creditCardNumberTextView.text?.characters.first == "3" {
    let validator = Validator(cardType: .americanExpress, value:  self.creditCardNumberTextView.text!).test()

      if validator == true {

       } else {

       }
   }

Funktioniert wunderbar in der APP Ich arbeite mit Kreditkarten.

//: Playground - noun: a place where people can play

import UIKit

let cardNumber = "1234 8940 8941 5678"
let aString  = cardNumber.components(separatedBy:" ")

var starString:String = ""

for i in 0...(aString.count - 2) {
    starString = "\(starString) \(getStars(aString[i]))"
}

let finalCardString = starString + " " + aString.last!
print(finalCardString)

func getStars(_ digitString:String) -> String {

    let digits = digitString.flatMap{Int(String($0))}

    switch digits.count {
        case 1:
            return "*"
        case 2:
            return "**"
        case 3:
            return "***"
        case 4:
            return "****"
        case 5:
            return "*****"
        case 6:
            return "******"
        case 7:
            return "*******"
        case 8:
            return "********"
        case 9:
            return "*********"
        default:
            return ""

        }
}

// Ausgabe **** **** **** 5678

hier ist die Änderung der Antwort von @sleeping_giant für Swift. Diese Lösung formatiert den Text im Format "xxxx-xxxx-xxxx-xxxx-xxxx" und akzeptiert keine Zahlen außerhalb dieses Bereichs.

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool
{
    if string == ""{
        return true
    }

    //range.length will be greater than 0 if user is deleting text - allow it to replace
    if range.length > 0
    {
        return true
    }

    //Don't allow empty strings
    if string == "-"
    {
        return false
    }

    //Check for max length including the spacers we added
    print(range.location)
    if range.location > 23
    {
        return false
    }

    var originalText = textField.text
    let replacementText = string.replacingOccurrences(of: "-", with: "")

    //Verify entered text is a numeric value
    let digits = NSCharacterSet.decimalDigits
    for char in replacementText.unicodeScalars
    {
        if !(digits as NSCharacterSet).longCharacterIsMember(char.value)
        {
            return false
        }
    }

    //Put an empty space after every 4 places
    if (originalText?.characters.count)! > 0
    {
        if (originalText?.characters.count)! < 5 && (originalText?.characters.count)! % 4 == 0{
            originalText?.append("-")
        }else if(((originalText?.characters.count)! + 1) % 5 == 0){
            originalText?.append("-")
        }

    }

    textField.text = originalText

    return true
}

Bitte verwenden Sie eine einfache Form der Gutschriftkarte /** Siehe Verwendungsbeispiel: ### let str = "41111111111111111"

 let x = yourClassname.setStringAsCardNumberWithSartNumber(4, withString: str!, withStrLenght: 8)

 ### output:- 4111XXXXXXXX1111

 let x = yourClassname.setStringAsCardNumberWithSartNumber(0, withString: str!, withStrLenght: 12)

 ### output: - XXXXXXXXXXXX1111

 */
func setStringAsCardNumberWithSartNumber(Number:Int,withString str:String ,withStrLenght len:Int ) -> String{
    //let aString: String = "41111111111111111"
    let arr = str.characters
    var CrediteCard : String = ""
    if arr.count > (Number + len) {
        for (index, element ) in arr.enumerate(){
            if index >= Number && index < (Number + len) {
                CrediteCard = CrediteCard + String("X")
            }else{
                CrediteCard = CrediteCard + String(element)
            }
        }
      return CrediteCard
    }else{
            print("\(Number) plus \(len) are grether than strings chatarter \(arr.count)")
    }
    print("\(CrediteCard)")
    return str
}

Ich hoffe das ist hilfreich für dich. 

Diese Antworten sind für mich einfach zu viel Code. Hier ist eine Lösung in Swift 2.2.1

extension UITextField {

    func setText(to newText: String, preservingCursor: Bool) {
        if preservingCursor {
            let cursorPosition = offsetFromPosition(beginningOfDocument, toPosition: selectedTextRange!.start) + newText.characters.count - (text?.characters.count ?? 0)
            text = newText
            if let newPosition = positionFromPosition(beginningOfDocument, offset: cursorPosition) {
                selectedTextRange = textRangeFromPosition(newPosition, toPosition: newPosition)
            }
        }
        else {
            text = newText
        }
    }
}

Nun fügen Sie einfach eine IBAction in Ihren View-Controller ein:

@IBAction func textFieldEditingChanged(sender: UITextField) {
    var digits = current.componentsSeparatedByCharactersInSet(NSCharacterSet.decimalDigitCharacterSet().invertedSet).joinWithSeparator("") // remove non-digits
    // add spaces as necessary or otherwise format your digits.
    // for example for a phone number or Zip code or whatever
    // then just:
    sender.setText(to: digits, preservingCursor: true)
}

Bitte überprüfen Sie die unten angeführte Lösung.

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

        let subString = (textField.text as! NSString).substringWithRange(range)
        if subString == " " && textField == cardNumberTextfield
        {
            return false     // user should not be able to delete space from card field
        }
        else if string == ""
        {
            return true      // user can delete any digit
        }


        // Expiry date formatting

        if textField == expiryDateTextfield
        {
            let str = textField.text! + string

            if str.length == 2 && Int(str) > 12
            {
                return false                  // Month should be <= 12
            }
            else if str.length == 2
            {
                textField.text = str+"/"      // append / after month
                return false
            }
            else if str.length > 5
            {
                return false                  // year should be in yy format
            }
        }



        // Card number formatting

        if textField == cardNumberTextfield
        {
            let str = textField.text! + string

            let stringWithoutSpace = str.stringByReplacingOccurrencesOfString(" ", withString: "")

            if stringWithoutSpace.length % 4 == 0 && (range.location == textField.text?.length)
            {
                if stringWithoutSpace.length != 16
                {
                    textField.text = str+" "    // add space after every 4 characters
                }
                else
                {
                    textField.text = str       // space should not be appended with last digit
                }

                return false
            }
            else if str.length > 19
            {
                return false
            }
        }



        return true
    }

in meinem Fall müssen wir eine iban-Nummer formulieren. Ich denke, der unten stehende Code-Block hilft dir

Prüfen Sie zunächst, ob der vom Benutzer eingegebene Wert gültig ist

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

    if(textField == self.ibanTextField){

           BOOL shouldChange =  ([Help checkTextFieldForIBAN:[NSString stringWithFormat:@"%@%@",textField.text,string]]);
 }
}

Zweitens sehen Sie eine iban-formatierte Methode wie unten. Unser iban-formatierter Brief beginnt mit 2 Buchstaben.

+(BOOL)checkTextFieldForIBAN:(NSString*)string{

    string = [string stringByReplacingOccurrencesOfString:@" " withString:@""];

    if ([string length] <= 26) {

        if ([string length] > 2) {

            if ([self isLetter:[string substringToIndex:2]]) {

                if ([self isInteger:[string substringFromIndex:2]])
                    return YES;
                else
                    return NO;

            }else {

                return NO;
            }
        }else{

            return [self isLetter:string];
        }

    }
    else {

        return NO;
    }

    return YES;
}