On OS X, does Objective-C compile to native code or byte-code?
Can Objective-C programs be compiled on Linux?
+2
A:
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.
Bill Williams
2008-10-05 20:40:08
I used to work as a GNUstep developer - still have the SVN commit flag but haven't actually done so in a while. It's a nice system and provides a good amount of source compatibility with Cocoa, but you'd be misguided if you thought that you could just take an arbitrary Mac app and type 'make'.
Graham Lee
2008-10-05 20:43:44
+11
A:
Objective-C is compiled to native code by either GCC or LLVM. You can compile ObjC programs on Linux (the generic GCC will happily support ObjC, though it uses a different runtime library than either of the Apple ones). For a cross-platform API similar to Cocoa (i.e. derived from Cocoa) which will happily work on Linux and let you port some code between OS X and Linux, check out GNUstep: http://www.gnustep.org
Graham Lee
2008-10-05 20:40:25
To clarify, for 'LLVM' read 'GCC using the LLVM back-end'. LLVM on it's own is not a compiler but a back-end machine-code generator.
2008-10-05 20:44:48
Apple is working on clang, a front-end to LLVM; GCC is not used at all in this path. It's not ready for production usage yet, though.
ephemient
2008-10-05 20:51:53
Also, Cocoa would be more accurately described as being derived from GNUStep (OpenStep) than the other way around.
Marcin
2008-10-05 21:26:56
@marcin Cocoa is a marketing term for Apple's OpenStep implementation[*], and GNUstep is derived from OpenStep…[*] a non-compliant implementation as it lacks the DPS functions ;-)
Graham Lee
2008-10-05 23:44:45