Xcode 4.2 Compilation Failed with prototype cell

Question

I\'m trying out the new Xcode 4.2 Beta and I\'m wondering if my code is wrong or if I\'m bumping in to an bug.

The new Storyboard feature is promising but extremely bug

Answer 1

I had to remove the folder for my project in ~/Library/Developer/Xcode/DerivedData/ and rebuild. You can find the name of that folder in the logs using Tony's procedure above.

EDIT: I now think this is a bug in Xcode (Version 4.2.1). It's intermittent for me. To fix it I have to rebuild, sometimes two or three times. Build/Clean doesn't seem to help.

EDIT 2: Ok, hopefully the real problem. I had two references to my storyboard in the project navigator (probably a remnant of copying/rebuilding the project). I just removed one of them (making sure to only delete the reference!). Seems likely to be the problem (Xcode compiling the same file twice simultaneously).