Unintended fun with Xcode 4.

I was working on a project, when something went very wrong -- in retrospect, I'm not sure it was even an error that I had introduced -- and once again, I had to restore my project files from a back-up.

I tried restoring the project files from three different sources, all, inexplicably, with the same errors! -- before I realized that the problem seemed to be that I was opening them from the same location as the project that had gone wrong (having copied over the project folders). When I opened those files from other locations, there were no errors.

Eventually, I chose to rename the project folder, and that solved the problem. (Who knows -- that might even have solved the problem with the original project files, as well.) Later on I was able to restore the original folder name, and while the error messages came up again, briefly, the project did build successfully.

I don't understand why Xcode seems so completely and utterly dependent on file locations. (At one point I had tried to reorganize some files outside of the program, just putting them in folders, but relinking to them proved to be so much trouble that I gave up on the whole idea.)