I‘m not entirely sure where this first started, but a pattern that you seen a lot in third party Objective-C libraries is using separate success/failure blocks for callback on asynchronous API. It’s surprising that is has caught on for a couple of reasons. The first is that most good Objective-C developers seem to want to do things the “the Apple way,” and Apple doesn’t use this pattern anywhere.
![Collin Donnell - Stop Using Success/Failure Blocks](https://cdn-ak-scissors.b.st-hatena.com/image/square/8d71ff5111e05619a10d29bb40d7aebaa75c8fbc/height=288;version=1;width=512/https%3A%2F%2Fs0.wp.com%2Fi%2Fblank.jpg)