When to use FOUNDATION_EXPORT?

Question

I am a bit confused as when we should use FOUNDATION_EXPORT in objective-c and what the purpose of that is? Can anyone explain in layman terms? Thanks!

Answer 1

When to use FOUNDATION_EXPORT?

Never.

FOUNDATION_EXPORT is an undocumented implementation detail of Apple's system frameworks so you should not use it at all.

Answer 2

When we should use FOUNDATION_EXPORT in Objective-c

Whenever you are importing foundation framework in Objective-C. It is the best practice to use FOUNDATION_EXPORT instead of extern. Because NSObjCRuntime.h in Foundation framework it includes c and c++ library. So for default visibility of the c and c++ symbols it compiles accordingly for making it more compatible.

Purpose of using FOUNDATION_EXPORT instead of extern:

1) Visible Symbolity

2) Compatibility to other source code.