I'm aware of all that, but of course you DO want to show things to the outside, all the time. I also know about the newer syntax, which is awesome the few times I still dip into ObjC, but I'm more thinking of map/each/select/detect/etc. There are builtin methods for doing those, but their sheer verbosity tends to discourage the sort of free and easy chaining that Ruby encourages. (Some might argue that's a benefit. Not me.)

Cocoa is a fantastic system to build on top of. NSDate is MILES better than the Ruby time stuff, for example. NS/UI solid core plus Ruby's flexible syntax and culture of sensible defaults is a marriage made in heaven.