键入密码时，键盘上方显示黑条

Question

在某些情况下，当我抬起键盘时，会看到以下内容：

但是在不同的设备上，我得到了：

为什么会这样？

这是我用于键盘处理的代码：

  //MARK: Keyboard handling

    private func registerKeyboardNotifications(){
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide), name: UIResponder.keyboardWillHideNotification, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardDidShow), name: UIResponder.keyboardDidShowNotification, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardDidHide), name: UIResponder.keyboardDidHideNotification, object: nil)
    }

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

    @objc func keyboardWillHide(notification: NSNotification) {

        if self.view.frame.origin.y != 0 {
            self.view.frame.origin.y = 0
        }
    }


    @objc func keyboardDidShow(notification:NSNotification){
        isKeyboardVisible = true

        if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {


            print("Keyboard size \(keyboardSize)")
        }
    }

    @objc func keyboardDidHide(notification:NSNotification){
        isKeyboardVisible = false


        if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {



        }
    }

我的文本字段的secureTextEntry属性设置为true。