没有使用 Objective-C 通知 UIKeyboardWillShowNotification 和 UIKeyboardWillHideNotification 选择器声明的方法

Question

在 Xcode 的最近更新后，该代码曾经有效，但不再有效。大多数 Selector(":") 都具有自动更正功能，但以下代码除外：

override func viewDidLoad() {
    super.viewDidLoad()

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

其中标记了一个错误：

No method declared with Objective C selector 'keyboardWillSHow:'

这张图片显示了不同的尝试，但都失败了。

此代码的新语法是什么？

Answer 1

swift 语法已更改。试试这个：

NSNotificationCenter.defaultCenter().addObserver(self, selector: #Selector(ClassThatHasTheSelector.keyboardWillShow), name:UIKeyboardWillShowNotification, object: nil);

Answer 2

分配 Selector 如下：

NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(YourClassName.keyboardWillShow(_:)), name:UIKeyboardWillShowNotification, object: nil);

以及更新你想要的方法：

func keyboardWillShow(notification: NSNotification) {

     //Update UI or Do Something

}

与 UIKeyboardWillHideNotification 相同的方法。

Answer 3

我遇到了同样的问题，并且还发现您所引用的 class 也必须是 NSObject 的子class（这不是necc. Swift 中的情况）否则你会收到消息

error: argument of '#selector' refers to instance method 'yourMethod(notification:)' that is not exposed to Objective-C"

Answer 4

Swift 3 语法（就像 Sohil 上面的一样）：

    func someMethod(sender: Any?) {
      ...
    }

    func someBlockCallingWithSelector() {
      someObject.addTarget(self, action: #selector(someMethod), for: .valueChanged) 
    }

Answer 5

Swift 3 例：

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

// MARK: - Actions

@objc private func keyboardWillShow(notification: Notification) {
    print("keyboardWillShow called")
}

@objc private func keyboardWillHide(notification: Notification) {
    print("keyboardWillHide called")
}

没有使用 Objective-C 通知 UIKeyboardWillShowNotification 和 UIKeyboardWillHideNotification 选择器声明的方法

No Method declared with Objective-C Selector for Notification UIKeyboardWillShowNotification and UIKeyboardWillHideNotification

keyboard

uitextfield

swift

xcode7

swift2.2