This bug has been driving me nuts since I started using Xcode (4.6.3). Whenever I try to link a Storyboard item to my code, I get the error:
Could not
I tried all of these answers, the problem for me was related to Xcode not being able to index the files. I fixed this by simply quitting Xcode and reopening the project. Of course I did that after trying all of the above solutions :p