var pointOfStackView: CGPoint?
    
var stackView: UIStackView!

override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillAppear), name: UIResponder.keyboardWillShowNotification, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide), name: UIResponder.keyboardWillHideNotification, object: nil)
    }
    
    @objc private func keyboardWillHide(notification: NSNotification) {
        
        guard let pointOfStackView = pointOfStackView else { return }
        
        stackView.center = pointOfStackView
    }
    
    @objc private func keyboardWillAppear(notification: NSNotification) {
        
        pointOfStackView = stackView?.center
        
        let userInfo = notification.userInfo!
        let keyboardFrame = (userInfo[UIResponder.keyboardFrameEndUserInfoKey] as! NSValue).cgRectValue
        
        stackView.center = CGPoint(x: view.center.x, y: view.frame.height - keyboardFrame.height - 16.0 - stackView.frame.height / 2)
    }