Swift鍵盤上升

override func viewDidLoad() {
        super.viewDidLoad()
//註冊
NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillShow(notification:)), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillHide(notification:)), name: NSNotification.Name.UIKeyboardWillHide, object: nil)

}

    func keyboardWillShow(notification:NSNotification) {
            if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
                if self.view.frame.origin.y == 0 {
                    self.view.frame.origin.y -= keyboardSize.height
                }
            }
        }
    func keyboardWillHide(notification:NSNotification) {

            if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
                if self.view.frame.origin.y != 0 {
                    self.view.frame.origin.y += keyboardSize.height
                }
            }

    }

override func viewWillDisappear(_ animated: Bool) {
        //刪除觀察者，避免傳輸不必要的訊息

        NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIKeyboardWillShow, object: self.view.window)
        NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIKeyboardWillHide, object: self.view.window)
    }