Update to my old post: http://www.virtualoutpost.com/2012/03/11/finding-xcodes…or-ios-devices

To find the iOS predefined macros For Xcode 6, type this into the terminal:

llvm-gcc -arch armv7 -dM -E – < /dev/null | sort

(Yes, there is a single dash by itself.)
Change the -arch option to “armv6” or “armv7” or “armv7s” as needed.