Here is the ControlExample running under cocoa:
We started on Monday with nothing. Along the way, we hit an Objective-C compiler bug involving struct return types that caused a series of Apple trolls to visit us, each one expressing increasing disbelief. No problem though, I love these low level compiler guys. They are smart and fun.
But crashing didn't stopped us. We just typed in custom natives each time we hit the problem and kept going. Eclipse allowed us to develop rapidly, almost as fast as the old Smalltalk days. Objective-C has lots of good stuff from Smalltalk like real meta-classes (Java static methods are crap) and dynamic dispatch.
The week was an almost perfect example of prototyping. The code we have is utter crap and we have cut every corner, however, we have learned the technology and explored the area. Prototyping is about reducing risk using a short term, high energy, low quality approach to prove that a solution is possible and scope the time frame.