It should be a category on NSObject so it supports anything that supports fast enumeration which could be anything. And the indentation in the above is correct. The way you've implemented it is "anti-conventional" and bad form, imho.
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.
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.