https://aaron.blog/tags/notifications/Recent content in Notifications on The Dangling PointerHugoen-usTue, 17 Dec 2013 15:22:37 +0000https://aaron.blog/nsnotificationcenter-block-based-observer-2/Tue, 17 Dec 2013 15:22:37 +0000https://aaron.blog/nsnotificationcenter-block-based-observer-2/<p>Back in iOS 4, a nifty block-based observer method was added to NSNotificationCenter:<br></p><ul><li><code>(id)addObserverForName:(NSString *)name object:(id)obj queue:(NSOperationQueue *)queue usingBlock:(void (^)(NSNotification *))block;</code><br></li></ul><p>Super convenient, right? I love using blocks to pass simple callbacks to controllers instead of creating a delegate protocol. There is a catch with this method, and it's not terribly obvious unless you're looking closely. The method returns (id) - according to Apple's documentation the return object is "An opaque object to act as the observer".  What does this mean?</p>