Some very interesting issues with iOS 6. Apple went and implemented a method in NSMutableArray with the same signature as one of my category methods. Hilarity ensued, but also a broken home screen.
I'm actually really thrilled that the try-catch was able to help the app recover correctly.
Edit: Actually it's the only feature of the iPhone app that is working. The new calendar view is just "Loading..." (iOS 6 -- my own fault)