当键盘快速显示时移动按钮

Question

在UIViewController中,我有几个文本字段,一个按钮位于UIViewController的底部.对于按钮,我设置了一个常量为0的底部约束.然后我从底部约束到UIViewController创建了一个出口.

当我运行我的代码时,按钮不会向上移动.我已经看到了关于stackoverflow的建议,我应该添加UIScrollView,但这意味着,我必须删除UIViewController上的所有对象,放置UIScrollView,然后再次将我的对象放在UIVIewController上.

   @IBOutlet weak var bottomConstraint: NSLayoutConstraint!    

    // When tapping outside of the keyboard, close the keyboard down
       override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    self.view.endEditing(true)
}

// Stop Editing on Return Key Tap. textField parameter refers to any textfield within the view

       func textFieldShouldReturn(textField: UITextField) -> Bool {
    textField.resignFirstResponder()
    return true
}



// when keyboard is about to show assign the height of the keyboard to bottomConstraint.constant of our button so that it will move up

     func keyboardWillShow(notification: NSNotification) {
if let userInfo = notification.userInfo {
    if let keyboardSize: CGRect = (userInfo[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() {

        bottomConstraint.constant = keyboardSize.size.height
        view.setNeedsLayout()
     }

   }
 }

  // When keyboard is hidden, move the button to the bottom of the view
func keyboardWillHide(notification: NSNotification) {
    bottomConstraint.constant = 0.0
    view.setNeedsLayout()
}

Answer 1

解决这个问题的典型方法是使用以下代码移动键盘:

在ViewController类中:

  func keyboardWillShow(notification: NSNotification) {

        if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() {
            if view.frame.origin.y == 0{
                let height = keyboardSize.height

                self.view.frame.origin.y += height
            }

        }

    }

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

        }
    }

在ViewDidLoad方法中:

 NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillShow:"), name: UIKeyboardWillShowNotification, object: nil)
 NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillHide:"), name: UIKeyboardWillHideNotification, object: nil)

请阅读: 不允许您尝试解决问题的方式.在上面的代码中,如果您更改view为按钮变量名称,按钮将会向上拍摄然后再向下.这是因为自动布局和程序布局不能一起工作,它是一个或另一个.解决这个问题的方法是通过编程方式创建该按钮(使用CGRect),然后使用上面的代码在键盘按下时仅移动该按钮.(通过更改view为按钮变量名称来执行此操作.

  func keyboardWillShow(notification: NSNotification) {

        if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() {
            if view.frame.origin.y == 0{
                let height = keyboardSize.height

                self.myButton.frame.origin.y += height
            }

        }

    }

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

        }
    }

要以编程方式创建按钮,您将使用与此类似的代码:

myButton.frame = CGRect(...)

Answer 2

对 Ryan 上面的回答的补充是，这可以通过自动布局来完成，不需要框架和 CGRect。

雨燕5

在您看来，像平常一样约束按钮，但添加对约束的引用，以便在键盘隐藏/显示时进行修改：

var bottomButtonConstraint = NSLayoutConstraint()

bottomButtonConstraint = yourButton.bottomAnchor.constraint(equalTo: safeAreaLayoutGuide.bottomAnchor, constant: -12)
bottomButtonConstraint.isActive = true

在你的 ViewController 中viewDidLoad()：

NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(notification:)), name: UIResponder.keyboardWillShowNotification, object: nil)

NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(notification:)), name: UIResponder.keyboardWillHideNotification, object: nil)

同样在你的 ViewController 中：

@objc private func keyboardWillShow(notification: NSNotification) {
    if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        self.yourCustomView.bottomButtonConstraint.constant -= keyboardSize.height
    }
}

@objc private func keyboardWillHide(notification: NSNotification) {
    self.yourCustomView.bottomButtonConstraint.constant = -12
}