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Dispatch and Receive events in ObjectiveC

/ Published in: Objective C
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thanks to http://stackoverflow.com/questions/2191594/how-to-send-and-receive-message-through-nsnotificationcenter-in-objective-c

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  1. @implementation TestClass
  2.  
  3. - (void) dealloc
  4. {
  5.     // If you don't remove yourself as an observer, the Notification Center
  6.     // will continue to try and send notification objects to the deallocated
  7.     // object.
  8.     [[NSNotificationCenter defaultCenter] removeObserver:self];
  9.     [super dealloc];
  10. }
  11.  
  12. - (id) init
  13. {
  14.     self = [super init];
  15.     if (!self) return nil;
  16.  
  17.     // Add this instance of TestClass as an observer of the TestNotification.
  18.     // We tell the notification center to inform us of "TestNotification"
  19.     // notifications using the receiveTestNotification: selector. By
  20.     // specifying object:nil, we tell the notification center that we are not
  21.     // interested in who posted the notification. If you provided an actual
  22.     // object rather than nil, the notification center will only notify you
  23.     // when the notification was posted by that particular object.
  24.  
  25.     [[NSNotificationCenter defaultCenter] addObserver:self
  26.                                              selector:@selector(receiveTestNotification:) 
  27.                                                  name:@"TestNotification"
  28.                                                object:nil];
  29.  
  30.     return self;
  31. }
  32.  
  33. - (void) receiveTestNotification:(NSNotification *) notification
  34. {
  35.     // [notification name] should always be @"TestNotification"
  36.     // unless you use this method for observation of other notifications
  37.     // as well.
  38.  
  39.     if ([[notification name] isEqualToString:@"TestNotification"])
  40.         NSLog (@"Successfully received the test notification!");
  41. }
  42.  
  43. @end
  44.  
  45. ... somewhere else in another class ...
  46.  
  47. - (void) someMethod
  48. {
  49.     // All instances of TestClass will be notified
  50.     [[NSNotificationCenter defaultCenter] postNotificationName:@"TestNotification" object:self];
  51. }

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