Does Objective-C compile to native code or byte-code?

Question

On OS X, does Objective-C compile to native code or byte-code?

Can Objective-C programs be compiled on Linux?

Answer 1

Yes, Objective-C compiles to machine code.

Objective-C compilers exist for Linux, but Cocoa is an OS X-only technology. I've heard of an open replacement called GNUstep, but don't know much about it.