xcode won't compile iOS apps, crashes when .xib or .storyboard files are opened

Question

I\'m running the very latest version of xcode (4.2.1). And I\'m signed up to the ios developer program.

When I create a new iOS Application for iPhone or iPad, using

Answer 1

I have same problem within xcode4.5 and iOS6. When I startup iOS simulator 6, it always report "The simulated application quit" and ask me to switch SDKS. Whatever I choose the right location of SDK5.0 or SDK6.0 for the simulator, the problem is still here. So I can't run even a simplest program with SDK6.0, but the old projects with SDK5.0 are ok.

I don't why, because it works well before today. So I follow @quellish's way, close xcode and simulator, remove these directory in my finder: ~/Library/Application\ Support/iPhone\ Simulator ~/Library/Application\ Support/Developer ~/Library/Developer

Then run Xcode again, everything goes ok again! thanks quellish!

I think some files in these directory was broken, so the strange problem happened. If someone know exactly why it happened, it's appreciate you can tell me.