NotificationCenter默认addObserver只在充电时起作用？

Question

我试图在键盘用于显示时向上移动我的文本字段，并在键盘隐藏时再次向下移动。所以我正在使用 NotificationCenter.default.addObserver 但这只有在充电时才能正常工作，而当我从充电器中取出时它不起作用，即它不会移动可能是这种情况。请帮我解决这个问题。提前致谢

下面是我的代码：

 override func viewDidLoad() {
    super.viewDidLoad()

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

   @objc 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 -= 50
        }
    }
}

@objc 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 += 50
        }
    }
}

Answer 1

问题是您使用的是 UIKeyboardFrameBeginUserInfoKey 而不是 UIKeyboardFrameEndUserInfoKey。

代码应该是：

@objc func keyboardWillShow(_ notification: Notification) {
    if let keyboardFrame: NSValue = notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue {
        let keyboardRectangle = keyboardFrame.cgRectValue
        let keyboardHeight = keyboardRectangle.height
    }
}

Answer 2

如果 self.view.frame.origin.y 是 0，则什么也不会发生。对吗？

@objc func keyboardWillShow(notification: NSNotification) {
    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        // If `origin.y` is `0`, then do nothing.
        if self.view.frame.origin.y != 0{
            self.view.frame.origin.y -= 50
        }
    }

@objc func keyboardWillHide(notification: NSNotification) {
    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        // If `origin.y` is `0` in `keyboardWillShow`, 
        // it will still be `0` here.
        // So, do nothing. 
        if self.view.frame.origin.y != 0{
            self.view.frame.origin.y += 50
        }
    }
}

NotificationCenter默认addObserver只在充电时起作用？

NotificationCenter default addObserver works only when charging?

ios

swift3