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Using NSNotificationCenter - posting a notification

/ Published in: Objective C
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  1. NSNotificationCenter.
  2.  
  3. Mutliple observers can be notified of events.
  4.  
  5. notification sent by a specific object...
  6. [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(myFooHappened:) name:MyFooNotification object:foo];
  7.  
  8. set object to nil to receive notifications of that name sent by ANY object.
  9. [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(myFooHappened:) name:MyFooNotification object:nil];
  10.  
  11. Format for myFooHappened is..
  12. -(void) myFooHappened:(NSNotification*)note {
  13.     // [note name] - name of notification [note object] - sender
  14.  
  15.     // [note userInfo] is an NSDictionary of key-value pairs filled by the sender. 
  16. }
  17.  
  18. Note: notifications are posted on the SAME THREAD as they were posted.
  19.  
  20. MUST unregister from all notifications in your dealloc
  21. -(void) dealloc
  22.     [[NSNotificationCenter defaultCenter] removeObserver:self];
  23. }
  24.  
  25. Posting a notification..
  26. Define a constant for the name of the notification..
  27. in .h
  28. extern NSString* const MyFooNotification;
  29.  
  30. in .m
  31. NSString* const MyFooNotification = @"MyFooNotification";
  32.  
  33. -(void) postFoo  {
  34. [[NSNotificationCenter defaultCenter] postNotificationName:MyFooNotification object:self userInfo:[NSDictionary ...]];

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