UITextField和UITextView輸入字數限制

extension UIViewController : UITextViewDelegate {
    
    func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
        return textView.text.count + (text.count - range.length) <= 30
    }
    
}

extension UIViewController : UITextFieldDelegate {
    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        return (textField.text?.count ?? 0) + (string.count - range.length) <= 11
    }
}