naming conventions - Objective C - Why do constants start with k

Question

Why do constants in all examples I've seen always start with k? And should I #define constants in header or .m file?

I'm new to Objective C, and I don't know C. Is there some tutorial somewhere that explains these sorts of things without assuming knowledge of C?

Answer 1

Starting constants with a "k" is a legacy of the pre-Mac OS X days. In fact, I think the practice might even come from way back in the day, when the Mac OS was written mostly in Pascal, and the predominant development language was Pascal. In C, #define'd constants are typically written in ALL CAPS, rather than prefixing with a "k".

As for where to #define constants: #define them where you're going to use them. If you expect people who #import your code to use the constants, put them in the header file; if the constants are only going to be used internally, put them in the .m file.