Swift 4, Swift 5
This method doesn’t use NSString
// MARK: - UITextFieldDelegate
extension MyViewController: UITextFieldDelegate {
func textField(_ textField: UITextField,
shouldChangeCharactersIn range: NSRange,
replacementString string: String) -> Bool {
if let text = textField.text,
let textRange = Range(range, in: text) {
let updatedText = text.replacingCharacters(in: textRange,
with: string)
myvalidator(text: updatedText)
}
return true
}
}
Note. Be careful when you use a secured text field.