How to reference files with environment variables?

I was wondering if someone manage to reference files (except headers or lib) with an environment variable in XCode (mine : v3.2.1) ?

There are settings that specify search paths for headers (HEADER_SEARCH_PATHS), libs (LIBRARY_SEARCH_PATHS), and even Carbon Resource (REZ_SEARCH_PATH). But how can I reference other file types for resources to have more flexibility for the development environment setup?

Ideally, I would like to include $(MY_RESOURCE)/my开发者_高级运维ResourceFile.foo.

A solution would be to force every developer to add the env var to Xcode Preferences->Source Trees. I would like to have exactly the same behavior but embedded in the .pbxproj.

Another solution, more flexible, but less maintainable would be to create a group, add files. Close XCode, edit the pbxproj and change the path with the env var.

Do someone have another simpler solution ?

I found a trick :

• Create a source tree with exactly the same name as the environment variable you want to use.
• Reference your data using the source tree.
• Delete the source tree.