"Unknown class in nib file"

[MacFiend]

Every so often, after I compile a build in XCode, I get this error:

"Unknown class 'XXX' in nib file. using 'NSObject' instead."

Where 'XXX' could be any one of the classes which my nib file uses. The error appears seemingly at random, and forces me to Clean All Targets. No biggie - I'm just wondering why this happens. It's kind of annoying to have to completely recompile my entire project, especially when in the middle of intense debugging (like right now).

[presterjohn]

Well I just ran into this problem, and lots of others have on the web.

The cause for me was the mystery "Class file not compiling" problem. Specifically, check your XCode project to see if the file checkbox is checked for the correct target.

Failure to compile the class file used in the nib may result in the symptoms described above.