Can't install my iOS 7 app to the iPhone Retina (4-inch 64-bit) iOS simulator

Question

I can run my app on a physical 64-bit device it runs fine. Also I can install other test apps to the 64-bit sim. However when I try to run and build my app on the sim it acts like it is about to start by zooming in on the icon but then it freezes with the icon zoomed in then crashes but Xcode's debugger doesn't show anything. Any ideas?

EDIT: Works fine on non-64 bit sims. I have reset all iOS sims. (/Users/xxx/Library/Application Support/iPhone Simulator). I have cleaned my project and build folder.

EDIT 2: When I start a new blank single view app it doesn't work either. So I think it's my Xcode install. The 'other' app that works in the 64-bit sim doesn't build a 64-bit binary.

Answer 1

Reinstalling Xcode fixed the issue.

I wonder if I helped start this issue by side loading the iOS 6 SDK along side the iOS 7 SDK so that I could submit an iOS 6 app to the App Store with Xcode 5.