What is a better practice when defining a const NSString object in objective-c?

Question

When i read colleagues\' code in my team, i usually found there were two different types of definition for const NSString objects:

static NSString const *

Answer 1

// Demo.h

FOUNDATION_EXPORT NSString *const MyFirstConstant;
FOUNDATION_EXPORT NSString *const MySecondConstant;

// Demo.m

NSString *const MyFirstConstant = @"FirstConstant";
NSString *const MySecondConstant = @"SecondConstant";