How to write limit a number of characters as textfild width. And when pasting text, how to cut off the text other than the textfield width?

Question

Limiting the length to a limit on the number of characters in textfield causes UIlabel lengths to vary depending on the different language.

So I want to make it possible to type only as a fixed textfield width.

How to write limit a number of characters as textfield width? And when pasting text, how to cut off the text other than the textfield width?

This is my code

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
if subtitleTextfield.text != nil {
   nsString = subtitleTextfield.text! as NSString
   nsString = nsString.replacingCharacters(in: range, with: string) as NSString
    }   else if subtitleTextfield.text != ""  {
   nsString = subtitleTextfield.text! as NSString
   nsString = nsString.replacingCharacters(in: range, with: string) as NSString

    } else if subtitleTextfield.text == "" {
        subtitleTextfield.text = ""
    }

    guard let texts = subtitleTextfield.text else { return true }
    let currentText = nsString as NSString
    if currentText.length > 45 {
        subtitleTextfield.text = currentText.substring(to: 45)
    }

    return currentText.length < 45
}