UIView在显示键盘时出现，但在我开始键入（快速）时消失了吗？

Question

I have a UIView container which holds a UITextField and two UIButtons (see image below).

I have written an extension which listens to a UIKeyboardWillShow notification and animates the UIView so that it binds to the keyboard when it shows.

This works perfectly, but as soon as I start typing the UIView disappears again.

Extension usage:

sendMessageView.bindToKeyboard()

UIView extension:

extension UIView {

    func bindToKeyboard() {

        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: NSNotification.Name.UIKeyboardWillShow, object: nil)

    }//end func

    @objc func keyboardWillShow(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)

    }//end func

}//end extension

UIView binds to keyboard when it is displayed:

UIView disappears (I suspect behind the keyboard to its original location) when typing:

Answer 1

Don't put an extension for the UIView itself. Just add your textBox view as a subview and set the bottom constraint of your view to be updating according to the height of the keyboard. If keyboard is present, set the constant to the negative value of height of the keyboard else set it to zero.

    private func setupView() {
        NotificationCenter.default.addObserver(self, selector: #selector(keyBoardShown(_:)), name: UIResponder.keyboardWillShowNotification, object: nil)
        self.view.backgroundColor = .white
        self.view.addSubview(textInputView)
        bottomConstraint = NSLayoutConstraint(item: textInputView, attribute: .bottom, relatedBy: .equal, toItem: view.safeAreaLayoutGuide, attribute: .bottom, multiplier: 1.0, constant: 0)
        NSLayoutConstraint.activate([
            //textBox.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: 0),
            //textInputView.heightAnchor.constraint(equalToConstant: UIFont.systemFontSize+14+10),
            textInputView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor, constant: 0),
            textInputView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor, constant: 0)
        ])
        bottomConstraint.isActive = true
    }

    @objc private func keyBoardShown(_ notification: NSNotification) {
        if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
            print(keyboardSize.height)
            bottomConstraint.constant = -keyboardSize.height
            UIView.animate(withDuration: 0.5,
                           delay: TimeInterval(0),
                           options: .beginFromCurrentState,
                           animations: { self.view.layoutIfNeeded() },
                           completion: nil)
        }
    }