Availability.h, UIKit.h, etc not found

Question

I\'m having a great problem here.

I recently downloaded Xcode 4.3 from the Mac App Store, because it had the full-screen feature for Lion. And then, my project stopp

Answer 1

I solved it just by reinstalling Xcode.

If something similar happens to you, delete Xcode.app (as it's now just an App), and download it again from the Mac App Store.

I guess it didn't install correctly.