LEGO Mindstorms NXT - NXC compiler for OS X
It is possible to use XCode. You need to download the NXC compiler (the linked page says NBC, but it included NXC as well). Then, write a Makefile that calls the NXC compiler.

If the compiler does not work on Yosemite, the source code is available from that link as well.

A detailed tutorial on using XCode with NXC can be found here.