Add NSNotificationCenter additions for block based observing about chocolate

[chaitanyagupta]

No longer needed. Use FXNotifications instead.

Quoting myself from earlier:

This solves two main problems with block based observers: 1) Inadvertently retaining self, and 2) Forgetting to remove the block based observation (which requires one to retain the returned observer object). The combination of 1 and 2 can lead to an even bigger memory leak where self is retained for the lifetime of the application. See [1] for more details.

So, for example, you could simply write this in init (if that’s where you want to observe the notification):

[[NSNotificationCenter defaultCenter] addObserver:self
                                         forName:NSSomeNotificationName
                                          object:nil
                                           queue:[NSOperationQueue mainQueue]
                                      usingBlock:^(NSNotification *note, id self) {
                                                     NSLog(@"self: %@", self); // look, no leaks!
                                                 }];

And be rest assured that the observation will go away when the “observer” is deallocated. It also returns an observation token just like the original API which can be used to manually remove the observation (e.g. when you need to observe/unobserve notifications in -viewWillAppear: and -viewDidAppear: respectively).

Also, because we shadow self in the observation block, there’s no danger of a leak (unless you reference an ivar directly!)

1. http://sealedabstract.com/code/nsnotificationcenter-with-blocks-considered-harmful/