Static, extern and inline in Objective-C

What do static, extern and inline (and their combinations) mean in Objetive-C using the LLVM compiler?

Also, I noticed that there are CG_EXTERN and CG_INLINE macros. Should we be using those instead?

(I couldn't find a source with a clear explanation so I thought it might be useful to create one here, or point to it if someone knows one)