I am attempting to send and receive messages through NSNotificationCenter
in Objective-C. However, I haven't been able to find any examples on how to do this. How do you send and receive messages through NSNotificationCenter
?
转载于:https://stackoverflow.com/questions/2191594/send-and-receive-messages-through-nsnotificationcenter-in-objective-c
To expand upon dreamlax's example... If you want to send data along with the notification
In posting code:
NSDictionary *userInfo =
[NSDictionary dictionaryWithObject:myObject forKey:@"someKey"];
[[NSNotificationCenter defaultCenter] postNotificationName:
@"TestNotification" object:nil userInfo:userInfo];
In observing code:
- (void) receiveTestNotification:(NSNotification *) notification {
NSDictionary *userInfo = notification.userInfo;
MyObject *myObject = [userInfo objectForKey:@"someKey"];
}
This one helped me:
// 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");
}
Source: http://www.smipple.net/snippet/Sounden/Simple%20NSNotificationCenter%20example
There is also the possibility of using blocks:
NSOperationQueue *mainQueue = [NSOperationQueue mainQueue];
[[NSNotificationCenter defaultCenter]
addObserverForName:@"notificationName"
object:nil
queue:mainQueue
usingBlock:^(NSNotification *notification)
{
NSLog(@"Notification received!");
NSDictionary *userInfo = notification.userInfo;
// ...
}];
if you're using NSNotificationCenter for updating your view, don't forget to send it from the main thread by calling dispatch_async
:
dispatch_async(dispatch_get_main_queue(),^{
[[NSNotificationCenter defaultCenter] postNotificationName:@"my_notification" object:nil];
});