A snippet to listen for all notifications inside an app for learning/exploring frameworks.

allnotifications.m

NSNotificationCenter *notifyCenter = [NSNotificationCenter defaultCenter];
[notifyCenter addObserverForName:nil
                          object:nil
                           queue:nil
                      usingBlock:^(NSNotification* notification){
                          // Explore notification
                          NSLog(@"Notification found with:"
                                "\r\n     name:     %@"
                                "\r\n     object:   %@"
                                "\r\n     userInfo: %@",
                                [notification name],
                                [notification object],
                                [notification userInfo]);
                      }];