Xcode "Use of undeclared identifier" errors, compiles/runs just fine

How are you including this class? In most cases I just include the class explicitly in header and/or body - instead of the *.pch file. Then this error goes away in my case.

Also deleting the derived data workes once in a while. Did you change the location in preferences recently by any chance. I also got this error when I use a ramdisk for derived data and then go back to default. This is the most annoying case - since it causes this error to appear then in almost every file.

This error seems to happen more often in Xcode 4.4 than the prior versions.

I was having the same problem and noticed that all of the undeclared identifiers were declared in files that were in my pch file.

With this in mind I deleted one of the #import lines from the pch file and recompiled which failed as expected. I then put the deleted line back in, recompiled and it compiled normally with all the false errors gone.

Hopefully this simple solution helps a few of you out if the above solutions don't.

Have you included the library files correctly? Take a look at that. Sometimes ARC issues might occur if we don't include the correct file, or something's missing or not connecting UI.

These kinds of errors are quite common with Xcode, unfortunately. It would be great if it would auto-refresh its error list all the time, but it doesn't always. When this happens, I strongly suggest that you restart Xcode, which will flush its error cache and hopefully solve your issues.