[platinumrad]

OS X is basically the XNU kernel (written mostly in C) + the FreeBSD userland (written mostly in C) + a few GNU utilities (written mostly in C) + a bunch of Apple stuff like iTunes, Safari, etc. (Written mostly in C++ and Objective-C). It's not really a "fork" of FreeBSD.

[pjmlp]

NeXTSTEP drivers were written in Objective-C, and OS X drivers are written in a C++ subset.