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

Need to count the kern for each character and remove it for the last character. There is example on Swift 5.3

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    
    let maxLength = 6
    let symbolWidth = CGFloat(43)
    let font = UIFont.systemFont(ofSize: 30)
    
    if string == "" { // when user remove text
        return true
    }
        
    if textField.text!.count + string.count - range.length > maxLength { // when user type extra text
        return false
    }
    
    let currentText = NSMutableAttributedString(attributedString: textField.attributedText ?? NSMutableAttributedString())
    currentText.deleteCharacters(in: range) // delete selected text
    var newStringLength = 0 
    
    for char in string{
        let newSymbol = NSMutableAttributedString(string: String(char))
        newSymbol.addAttribute(.font, value: font, range: NSMakeRange(0, 1))
        let currentSymbolWidth = newSymbol.size().width
        let kern = symbolWidth - currentSymbolWidth
        newSymbol.addAttribute(.kern, value: kern, range: NSMakeRange(0,1))
        
        currentText.insert(newSymbol, at: range.location + newStringLength)
        newStringLength += 1
    }
    
    if currentText.length == maxLength{
        currentText.addAttribute(.kern, value: 0, range: NSMakeRange(maxLength - 1, 1))
    }
    
    textField.attributedText = currentText
    
    return false

}