In my project, I\'ve include a full \"shared\" folder by link (not copy) that is outside my project folder.
In the .pch file, I have #import \"MyStandardHeader.h
Another thing to try -- just deleting Derived Data wasn't working for me, but this did:
Delete Derived Data using the Organizer window, Projects tab.
In your target settings delete the value (path) set for "Prefix Header"
Close XCode and restart. Reload your project. Let it re-index.
Restore the "Prefix Header" setting.
What a major PITA.