How to set letter spacing of UITextField

Question

I have an app in which the user has to type a four digit pin code. All digits have to be at a set distance from each other.

Is there a way to do this if the PinTex

Answer 1

This is what eventually worked to set the kern for every change

    textField.addTarget(self, action: "textFieldDidChange", forControlEvents: .EditingChanged)

    func textFieldDidChange () {    
        let attributedString = NSMutableAttributedString(string: textField.text)
        attributedString.addAttribute(NSKernAttributeName, value: 5, range: NSMakeRange(0, count(textField.text)))
        attributedString.addAttribute(NSFontAttributeName, value: font, range: NSMakeRange(0, count(textField.text)))
        attributedString.addAttribute(NSForegroundColorAttributeName, value: UIColor.blackColor(), range: NSMakeRange(0, count(textField.text)))

        textField.attributedText = attributedString
    }

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

        if count(textField.text) < 4 {
            return true
            // Else if 4 and delete is allowed
        }else if count(string) == 0 {
            return true
            // Else limit reached
        }else{
            return false
        }
    }

The problem however remains because different numbers have different widths, I will just resort back to making a UITextField for every digit.