在Objective-C中通过NSNotificationCenter发送和接收消息？

我试图通过Objective-C中的NSNotificationCenter发送和接收消息。 但是，我还没有find任何有关如何做到这一点的例子。 你如何通过NSNotificationCenter发送和接收消息？

Answer 1

 @implementation TestClass - (void) dealloc { // If you don't remove yourself as an observer, the Notification Center // will continue to try and send notification objects to the deallocated // object. [[NSNotificationCenter defaultCenter] removeObserver:self]; [super dealloc]; } - (id) init { self = [super init]; if (!self) return nil; // Add this instance of TestClass as an observer of the TestNotification. // We tell the notification center to inform us of "TestNotification" // notifications using the receiveTestNotification: selector. By // specifying object:nil, we tell the notification center that we are not // interested in who posted the notification. If you provided an actual // object rather than nil, the notification center will only notify you // when the notification was posted by that particular object. [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(receiveTestNotification:) name:@"TestNotification" object:nil]; return self; } - (void) receiveTestNotification:(NSNotification *) notification { // [notification name] should always be @"TestNotification" // unless you use this method for observation of other notifications // as well. if ([[notification name] isEqualToString:@"TestNotification"]) NSLog (@"Successfully received the test notification!"); } @end 

另外一个class的其他地方

 - (void) someMethod { // All instances of TestClass will be notified [[NSNotificationCenter defaultCenter] postNotificationName:@"TestNotification" object:self]; } 

Answer 2

扩展dreamlax的例子 …如果你想发送数据和通知一起

在发布代码中：

 NSDictionary *userInfo = [NSDictionary dictionaryWithObject:myObject forKey:@"someKey"]; [[NSNotificationCenter defaultCenter] postNotificationName: @"TestNotification" object:nil userInfo:userInfo]; 

在观察代码中：

 - (void) receiveTestNotification:(NSNotification *) notification { NSDictionary *userInfo = notification.userInfo; MyObject *myObject = [userInfo objectForKey:@"someKey"]; } 

Answer 3

也有使用块的可能性：

 NSOperationQueue *mainQueue = [NSOperationQueue mainQueue]; [[NSNotificationCenter defaultCenter] addObserverForName:@"notificationName" object:nil queue:mainQueue usingBlock:^(NSNotification *notification) { NSLog(@"Notification received!"); NSDictionary *userInfo = notification.userInfo; // ... }]; 

苹果的文档

Answer 4

这个帮了我：

 // Add an observer that will respond to loginComplete [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(showMainMenu:) name:@"loginComplete" object:nil]; // Post a notification to loginComplete [[NSNotificationCenter defaultCenter] postNotificationName:@"loginComplete" object:nil]; // the function specified in the same class where we defined the addObserver - (void)showMainMenu:(NSNotification *)note { NSLog(@"Received Notification - Someone seems to have logged in"); } 

资料来源： http : //www.smipple.net/snippet/Sounden/Simple%20NSNotificationCenter%20example

Answer 5

如果您使用NSNotificationCenter更新视图，请不要忘记通过调用dispatch_async从主线程发送它：

 dispatch_async(dispatch_get_main_queue(),^{ [[NSNotificationCenter defaultCenter] postNotificationName:@"my_notification" object:nil]; });