我们也应该删除通知。

Ex.

deinit 
{
  NotificationCenter.default.removeObserver(self, name:NSNotification.Name(rawValue: "notify"), object: nil)

}

Declare a notification name extension Notification.Name { static let purchaseDidFinish = Notification.Name("purchaseDidFinish") } You can add observer in two ways: Using Selector NotificationCenter.default.addObserver(self, selector: #selector(myFunction), name: .purchaseDidFinish, object: nil) @objc func myFunction(notification: Notification) { print(notification.object ?? "") //myObject print(notification.userInfo ?? "") //[AnyHashable("key"): "Value"] } or using block NotificationCenter.default.addObserver(forName: .purchaseDidFinish, object: nil, queue: nil) { [weak self] (notification) in guard let strongSelf = self else { return } strongSelf.myFunction(notification: notification) } func myFunction(notification: Notification) { print(notification.object ?? "") //myObject print(notification.userInfo ?? "") //[AnyHashable("key"): "Value"] } Post your notification NotificationCenter.default.post(name: .purchaseDidFinish, object: "myObject", userInfo: ["key": "Value"])

iOS 9和OS X 10.11。它不再需要一个 NSNotificationCenter观察者取消注册 收回。更多信息

对于基于块的实现，如果你想在块中使用self，你需要做一个弱-强舞蹈。更多信息

基于块的观察者需要删除更多信息

let center = NSNotificationCenter.defaultCenter()
center.removeObserver(self.localeChangeObserver)

我们也应该删除通知。

Ex.

deinit 
{
  NotificationCenter.default.removeObserver(self, name:NSNotification.Name(rawValue: "notify"), object: nil)

}

Swift 5和Xcode 10.2:

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

它与Objective-C API相同，但使用了Swift的语法。

Swift 4.2和Swift 5:

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

如果你的观察者没有从Objective-C对象继承，你必须用@objc作为你的方法的前缀来使用它作为选择器。

@objc private func batteryLevelChanged(notification: NSNotification){     
    //do stuff using the userInfo property of the notification object
}

参见NSNotificationCenter类参考，与Objective-C api交互

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)