Here is the ControlExample running under cocoa:
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.