textView shouldChangeTextIn范围破坏了我的按钮bindToKeyboard函数

Question

我有一个textView使用textView shouldChangeTextIn函数仅允许一定数量的字符，我也有一个将按钮绑定到键盘的函数，问题是当我使用shouldChangeTextIn范围函数将键盘解除绑定时，如何我可以解决这个问题吗？我在viewDidLoad中调用bindToKeyboard

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {

        self.amountLabel.isHidden = false

        var amount = 0
        var count = self.textView.text?.count

        amount = 280 - count!
        self.amountLabel.text = String(amount)
        if(amount <= 0){
            self.textView.text?.remove(at: (self.textView.text?.index(before: (self.textView.text?.endIndex)!))!)
        }



        return true
    }

extension UIView {
    func bindToKeyboard(){
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillChange(_:)), name: NSNotification.Name.UIKeyboardDidChangeFrame, object: nil)

    }
    @objc func keyboardWillChange(_ notification: NSNotification){

        let duration = notification.userInfo![UIKeyboardAnimationDurationUserInfoKey] as! Double
        let curve = notification.userInfo![UIKeyboardAnimationCurveUserInfoKey] as! UInt
        let beginningFrame = (notification.userInfo![UIKeyboardFrameBeginUserInfoKey] as! NSValue).cgRectValue
        let endFrame = (notification.userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue).cgRectValue
        let deltaY = endFrame.origin.y - beginningFrame.origin.y


        UIView.animateKeyframes(withDuration: duration, delay: 0.0, options: UIViewKeyframeAnimationOptions(rawValue: curve), animations: {
            self.frame.origin.y += deltaY
        }, completion: nil)
    }

}