Question

当我使用以下代码时：

override func viewDidLoad() {
    nc = NotificationCenter.default
    nc.addObserver(self, selector: #selector(self.receivedNotification), name:MyNotification, object: nil)
}       


func receivedNotification() -> void {
    NSLog("notification received")
}

receivedNotification永远不会被称为

但是当我使用以下关闭方式时

nc.default.addObserver(forName:MyNotification, object:nil, queue:nil) {
    notification in
        NSLog("notification received")
}

成功调用

NSLog("...")。

有人可以解释一下这里发生了什么

Answer 1

接收（获取）通知

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

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

发送（发布）通知：

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

停止收听通知

NotificationCenter.default.removeObserver(self, name: "NotificationIdentifier", object: nil);

Answer 2

请尝试以下代码。它成功调用了nslog。

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
  let nc = NotificationCenter.default
    nc.addObserver(self, selector: #selector(self.receivedNotification), name:NSNotification.Name(rawValue: "MyNotification"), object: nil)
}


func receivedNotification() {
    NSLog("notification received")
}

//发布通知

let nc = NotificationCenter.default
    nc.post(name: NSNotification.Name(rawValue: "MyNotification"), object: nil)

Answer 3

您可以使用此方法获取名为

的本地通知

 override func viewDidLoad() {
    nc = NotificationCenter.default
    nc.addObserver(forName:MyNotification, object:nil, queue:nil, using:receivedNotification)
}

func receivedNotification() -> void {
    NSLog("notification received")
}

并发布通知

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

通知addObserver使用标准方式无响应

3 个答案: