键盘快速出现时移动按钮

Question

在 UIViewController 中，我有几个文本字段，并且按钮位于 UIViewController 的底部。 对于按钮，我设置了一个常数为 0 的底部约束。 然后我做了一个从底部约束到 UIViewController 的出口。

当我运行我的代码时，按钮不会向上移动。我在 stackoverflow 上看到了我应该添加 UIScrollView 的建议，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

解决此问题的典型方法是使用如下代码移动键盘：

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：

  NotificationCenter.default.addObserver(self, selector: Selector("keyboardWillShow:"), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
  NotificationCenter.default.addObserver(self, selector: Selector("keyboardWillHide:"), name: NSNotification.Name.UIKeyboardWillHide, 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，如果您将view 更改为您的按钮变量名称，则该按钮将向上弹起，然后又落下。这是因为自动布局和程序化布局不能一起使用，只能是其中之一。解决此问题的方法是通过编程创建该按钮（使用 CGRect），然后使用上面的代码在键盘按下时仅移动该按钮。 （通过将 view 更改为您的按钮变量名称来做到这一点。

   func keyboardWillShow(notification: NSNotification) {

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

要以编程方式创建按钮，您将使用类似于以下的代码：

myButton.frame = CGRect(...)

Answer 2

你需要添加(viewDidLoad) 观察者来调用你的函数：

NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(keyboardWillShow), name: UIKeyboardDidShowNotification, object: nil)
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(keyboardWillHide), name: UIKeyboardDidHideNotification, object: nil)

Answer 3

补充 Ryan 上面的回答，这可以通过自动布局完成，不需要框架和 CGRect。

斯威夫特 5

在您看来，像往常一样约束您的按钮，但添加对约束的引用以在键盘隐藏/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 的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)

也在你的 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
}

Answer 4

考虑使用这个 pod：https://cocoapods.org/pods/IQKeyboardManager 在 AppDelegate.swift 中，只需导入 IQKeyboardManagerSwift 框架并启用 IQKeyboardManager。

导入 IQKeyboardManagerSwift

@UIApplicationMain 类 AppDelegate: UIResponder, UIApplicationDelegate {

var window: UIWindow?

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

  IQKeyboardManager.shared.enable = true

  return true
}

}