Xcode 8中的Swift 3.0

Swift 3.0已经用结构“包装器类型”取代了许多“字符串类型”的api, NotificationCenter也是如此。通知现在由struct notification标识。名称而不是字符串。参见迁移到Swift 3指南。

以前的用法:

// Define identifier
let notificationIdentifier: String = "NotificationIdentifier"

// Register to receive notification
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(YourClassName.methodOfReceivedNotification(_:)), name: notificationIdentifier, object: nil)

// Post a notification
NSNotificationCenter.defaultCenter().postNotificationName(notificationIdentifier, object: nil)

Swift 3.0的新用法:

// Define identifier
let notificationName = Notification.Name("NotificationIdentifier")

// Register to receive notification
NotificationCenter.default.addObserver(self, selector: #selector(YourClassName.methodOfReceivedNotification), name: notificationName, object: nil)

// Post notification
NotificationCenter.default.post(name: notificationName, object: nil)

所有系统通知类型现在都定义为notification . name上的静态常量;例如。uidevicebatteryleveldidchange， . uiapplicationdidfinishlaunching， . uitextfieldtextdidchange等。

您可以扩展通知。使用您自己的自定义通知命名，以便与系统通知保持一致:

// Definition:
extension Notification.Name {
    static let yourCustomNotificationName = Notification.Name("yourCustomNotificationName")
}

// Usage:
NotificationCenter.default.post(name: .yourCustomNotificationName, object: nil)

NSNotificationCenter在iOS 11的Swift 4.0中添加了观察者语法

  NotificationCenter.default.addObserver(self, selector: #selector(keyboardShow), name: NSNotification.Name.UIKeyboardWillShow, object: nil)

这是为keyboardWillShow通知名称类型。其他类型可以从可用选项中选择

选择器的类型是@objc func，它处理键盘的显示方式(这是你的用户函数)

Swift 5通知观察员

override func viewDidLoad() {
    super.viewDidLoad() 
    NotificationCenter.default.addObserver(self, selector: #selector(batteryLevelChanged), name: UIDevice.batteryLevelDidChangeNotification, object: nil)
}

@objc func batteryLevelChanged(notification : NSNotification){
    //do here code
}

override func viewWillDisappear(_ animated: Bool) {
    NotificationCenter.default.removeObserver(self, name: UIDevice.batteryLevelDidChangeNotification, object: nil)

}

Swift 4.0 & Xcode 9.0+:

发送(Post)通知:

NotificationCenter.default.post(name: Notification.Name("NotificationIdentifier"), object: nil)

OR

NotificationCenter.default.post(name: Notification.Name("NotificationIdentifier"), object: nil, userInfo: ["Renish":"Dadhaniya"])

得到(获得)通知:

NotificationCenter.default.addObserver(self, selector: #selector(self.methodOfReceivedNotification(notification:)), name: Notification.Name("NotificationIdentifier"), object: nil)

接收到的通知的函数方法处理程序:

@objc func methodOfReceivedNotification(notification: Notification) {}

Swift 3.0 & Xcode 8.0+:

发送(Post)通知:

NotificationCenter.default.post(name: Notification.Name("NotificationIdentifier"), object: nil)

得到(获得)通知:

NotificationCenter.default.addObserver(self, selector: #selector(YourClassName.methodOfReceivedNotification(notification:)), name: Notification.Name("NotificationIdentifier"), object: nil)

接收到的通知的方法处理程序:

func methodOfReceivedNotification(notification: Notification) {
  // Take Action on Notification
}

删除通知:

deinit {
  NotificationCenter.default.removeObserver(self, name: Notification.Name("NotificationIdentifier"), object: nil)
}

Swift 2.3和Xcode 7:

发送(Post)通知

NSNotificationCenter.defaultCenter().postNotificationName("NotificationIdentifier", object: nil)

得到(获得)通知

NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(YourClassName.methodOfReceivedNotification(_:)), name:"NotificationIdentifier", object: nil)

接收的通知的方法处理程序

func methodOfReceivedNotification(notification: NSNotification){
  // Take Action on Notification
}

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对于历史上的Xcode版本…

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发送(Post)通知

NSNotificationCenter.defaultCenter().postNotificationName("NotificationIdentifier", object: nil)

得到(获得)通知

NSNotificationCenter.defaultCenter().addObserver(self, selector: "methodOfReceivedNotification:", name:"NotificationIdentifier", object: nil)

删除通知

NSNotificationCenter.defaultCenter().removeObserver(self, name: "NotificationIdentifier", object: nil)
NSNotificationCenter.defaultCenter().removeObserver(self) // Remove from all notifications being observed

接收的通知的方法处理程序

func methodOfReceivedNotification(notification: NSNotification) {
  // Take Action on Notification
}

用@objc注释类或目标方法

@objc private func methodOfReceivedNotification(notification: NSNotification) {
  // Take Action on Notification
}

// Or

dynamic private func methodOfReceivedNotification(notification: NSNotification) {
  // Take Action on Notification
}

这是一个非常简单的自定义通知观察者和post的例子

添加通知观察员

NotificationCenter.default.addObserver(self, selector: #selector(myFunction), name: Notification.Name("CustomeNotificationName"), object: nil)

添加选择器并处理观察者调用

@objc func myFunction(notification: Notification) {
    
    //Write you code
}

在需要时发布通知(观察员)。

NotificationCenter.default.post(name: NSNotification.Name("CustomeNotificationName"), object: "Object", userInfo: ["key":"Value"])

注意:-当你离开屏幕时，你需要删除观察者。如。

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
    NotificationCenter.default.removeObserver(self);
}

Swift 5和Xcode 10.2:

NotificationCenter.default.addObserver(
            self,
            selector: #selector(batteryLevelDidChangeNotification),
            name: UIDevice.batteryLevelDidChangeNotification,
            object: nil)