Adding space between textfield character when typing in text filed

Question

I have a textfield with maximum character range 16, After every 4 characters, I want to add minus character or space and then writing The rest of the characters like this sample 5022-2222-2222-2222. there is my code but that's don't work, how can do this?

if textField.text?.characters.count  == 5 {

               let  l = textField.text?.characters.count
            let attributedString = NSMutableAttributedString(string: cartNumberTextField.text!)
            attributedString.addAttribute(NSKernAttributeName, value: CGFloat(4.0), range: NSRange(location: l!, length: 4))
            cartNumberTextField.attributedText = attributedString

            }

            else if textField.text?.characters.count  == 9 {

                let  l = textField.text?.characters.count
                let attributedString = NSMutableAttributedString(string: cartNumberTextField.text!)
                attributedString.addAttribute(NSKernAttributeName, value: CGFloat(4.0), range: NSRange(location: l!, length: 4))
                cartNumberTextField.attributedText = attributedString

            }

            else if textField.text?.characters.count  == 13 {

                let  l = textField.text?.characters.count
                let attributedString = NSMutableAttributedString(string: cartNumberTextField.text!)
                attributedString.addAttribute(NSKernAttributeName, value: CGFloat(4.0), range: NSRange(location: l!, length: 4))
                cartNumberTextField.attributedText = attributedString

            }

I am adding this code in UITextField shouldChangeCharactersIn range method.

Answer 1

Use shouldChangeCharactersIn like this way.

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    if [6, 11, 16].contains(textField.text?.count ?? 0) && string.isEmpty {
        textField.text = String(textField.text!.dropLast())
        return true
    }
    let text = NSString(string: textField.text ?? "").replacingCharacters(in: range, with: string).replacingOccurrences(of: "-", with: "")
    if text.count >= 4 && text.count <= 16 {
        var newString = ""
        for i in stride(from: 0, to: text.count, by: 4) {
            let upperBoundIndex = i + 4
            let lowerBound = String.Index.init(encodedOffset: i)
            let upperBound = String.Index.init(encodedOffset: upperBoundIndex)
            if upperBoundIndex <= text.count  {
                newString += String(text[lowerBound..<upperBound]) + "-"
                if newString.count > 19 {
                   newString = String(newString.dropLast())
                }
            }
            else if i <= text.count {
                newString += String(text[lowerBound...])
            }
        }
        textField.text = newString
        return false
    }
    if text.count > 16 {
        return false
    }
    return true
}

Note: I have used - (Hyphen) you can simply replace it with Space if you want Space instead of - (Hyphen).

Edit: Code is edited to latest swift 4.*, for older swift version please check edit history.

Answer 2

To do it "on the fly", I connected Editing changed to this IBAction ; needs also to care for backspace

 @IBAction func editingTestField(_ sender: UITextField) {
      if sender.text!.count > 0 && sender.text!.count % 5 == 0 && sender.text!.last! != "-" {
         sender.text!.insert("-", at:sender.text!.index(sender.text!.startIndex, offsetBy: sender.text!.count-1) )
      }
 }

Answer 3

Took @claude31's simple solution and cleaned it up a bit. Also avoids issues with leading/trailing whitespace now. Just hook it up to your UITextField's Editing Changed event.

@IBAction func editingTextField(_ sender: UITextField) {
    let text = sender.text?.trim ?? ""
    if !text.isEmpty && text.count % 5 == 0 && text.last != "-" {
        sender.text = text  // trim whitespace before appending
        sender.text?.insert("-", at: text.index(text.startIndex, offsetBy: text.count - 1))
    }
}

Answer 4

Swift-5 conversion of @dfrib's answer.

extension Collection {
    public func chunk(n: Int) -> [SubSequence] {
        var res: [SubSequence] = []
        var i = startIndex
        var j: Index
        while i != endIndex {
            j = index(i, offsetBy: n, limitedBy: endIndex) ?? endIndex
            res.append(self[i..<j])
            i = j
        }
        return res
    }
}