What does the error File type mismatch (~) mean?

After upgrading to a newer version of Xcode, when I build my project I get and error:

File type mismatch (~), OutputModelPref开发者_运维知识库s.nib.

I have tried Googling and the Apple Developer Forum but I can't find out exactly what the problem is. Can anyone shed any light on what the problem might be?

Xcode stores file type information in foo.xcodeproj/project.pbxproj. Maybe you should open that file in a text editor and see if there's anything conspicuous. Look for lastKnownFileType =. If that doesn't help, maybe recreating the project will.

BTW: is that really a . nib file, not a .xib file?

I'm not sure what exactly this means, I got it in a slightly different place. Mine was complaining about a .pbxindex file with the same error message. In my case, I deleted the .pbxindex and rebuilt. After that the file was regenerated an all was fine. More info on my error here: What is Xcode pbxstrings file for?