xcode4: reliably detect the DerivedData directory of a project/workspace

Question

Xcode 4 builds everything into $HOME/Library/Developer/Xcode/DerivedData/$PROJECT-$UUID, where $UUID is a seemingly random string (it's not really random, it just looks random).

How can I reliably detect the $PROJECT-$UUID part of the above? I've seen a script (https://gist.github.com/949831) that guesses by assuming it is the last modified directory in DerivedData -- but that's not true if my CI machine is building a few projects in parallel.

Answer 1

Nobody answered, so I kept looking for ideas until I found the one below, which satisfies my needs. It can be further modified to be even safer.

1. In Xcode, add a run-script build phase to the target (the main target, if building a few for the same project).
2. In the script, put this line:

ln -sf "$BUILD_DIR" BuildDir

Now, when the target is built a symlink to the project's DerivedData directory will be created in the project directory. If desirable, you can also/instead create BuildDir as a file who's content is the $BUILD_DIR:

echo "$BUILD_DIR" > BuildDir

Then in a script use $(cat BuildDir) to retrieve it.