I have a problem with Xcode that I can\'t seem to resolve. I have a view controller lets call \"foobarViewController\", there was a \"foobarViewController.xib\" to accompany
check out this post: How to Empty Caches and Clean All Targets Xcode 4
"Command-Option-Shift-K to clean out the build folder. Even better, quit Xcode and clean out Library/Developer/Xcode/DerivedData manually. Remove all its contents because there's a bug where Xcode will run an old version of your project that's in there somewhere.
In the simulator, choose iOS Simulator > Reset Content and Settings.
Finally, for completeness, you can delete the contents of /var/folders; some caching happens there too." - Matt