[CMake] Detecting Xcode in CMake scripts

[Tron Thomas]

I currently have a project that I configure using CMake 2.8, and because 
of a problem with Xcode on the Macintosh I need to add some checks and 
adjust things in the CMake scripts to change the build configuration 
when Xcode is the intended build tool.  I would like to restrict these 
changes specifically to Xcode so that when a different tools like make 
files are used the special changes are not needed.

How could someone target specific build configuration settings to a 
development tool like Xcode?