ios - Are NSNotificationCenter events received synchronously or asynchronously? -

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if class registers nsnotificationcenter events of type , class posts event of type, code in receiver execute before (synchronously) or after (asynchronously) posting class continues? 

- (void)poster {     [[nsnotificationcenter defaultcenter]         postnotificationwithname:@"myevent"         object:nil];     nslog(@"hello poster"); }  - (void)receiver {     [[nsnotificationcenter defaultcenter]         addobserver:self         selector:@selector:(myselector)         name:@"myevent"         object:nil]; }  - (void) myselector:(nsnotification *) notification {     nslog(@"hello receiver"); }

in code example above, "hello receiver" printed before or after "hello caller"?

as stated in documentation nsnotificationcenter nsnotificationcenter class reference notifications posted synchronously.

a notification center delivers notifications observers synchronously. in other words, postnotification: methods not return until observers have received , processed notification. send notifications asynchronously use nsnotificationqueue.

in multithreaded application, notifications delivered in thread in notification posted, may not same thread in observer registered itself.

hope helps you.


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