I have an Xcode project that contains many sub-projects. The main project file and all sub-projects have the same xcconfig file. Some of the sub-projects currently have a build rule set on them to use the Intel compiler for C++ files. I'm wondering if there is a way to move this build rule into the xcconfig file so that I can easily turn on or off the Intel compiler for C++ files by changing just the one xcconfig file instead of having to modify the build rule for each sub-project