That's not what he's doing, he's exposing blocks as properties because he couldn't wrap his head around indentation which is the wrong motivation. Maybe read the source before condescending next time.
Uh, I did read it. Yes, it's a bad idea. So is adding random things to NSObject for protocols that it does not conform to. That's actually worse, I'd argue, since you suddenly have -[UIColor map:]. What does that do? Pass RGBA NSNumbers to the block and return a new color? Throw an exception? Silently disregard the message and return nil? At least this approach has type checking.
Just declare a normal function, which can correctly throw a compiler warning if you try to pass anything that does not conform to NSFastEnumeration to it.
That's not what he's doing, he's exposing blocks as properties because he couldn't wrap his head around indentation which is the wrong motivation. Maybe read the source before condescending next time.