I've just created a 1 hour tutorial/screencast that demonstrates TDD in objective-C (iOS 5) via Roy Osherove's Calculator Kata. The screencast primarily uses JetBrains' new AppCode IDE for objective-C, but it also flips occasionally into XCode 4.2 to set up a storyboard with a simple UIViewController that connects to the TDD-created Calculator class.
The screencast demonstrates a variety of layouts and keyboard shortcuts for AppCode (and to a lesser extent, XCode) as well as covering a number of language features of objective-C.
Please have a look, and if you have any questions, send me a comment at my twitter account.
Screencast: Learning Objective-C via TDD and Calculator Kata