ios - objective - gcmmessageidkey

¿Enviar y recibir mensajes a través de NSNotificationCenter en Objective-C?

Question

Estoy intentando enviar y recibir mensajes a través de NSNotificationCenter en Objective-C. Sin embargo, no he podido encontrar ningún ejemplo sobre cómo hacer esto. ¿Cómo se envían y reciben mensajes a través de NSNotificationCenter ?

Answer 1

Este me ayudó

// 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");
}

Fuente: http://www.smipple.net/snippet/Sounden/Simple%20NSNotificationCenter%20example

Answer 2

Para ampliar el ejemplo de Dreamlax ... Si desea enviar datos junto con la notificación

En el código de publicación:

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

En el código de observación:

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

Answer 3

Si está utilizando NSNotificationCenter para actualizar su vista, no olvide enviarlo desde el hilo principal llamando a dispatch_async :

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

Answer 4

También existe la posibilidad de utilizar bloques:

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

La documentación de apple

Answer 5

@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

... en otro lugar en otra clase ...

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