Objective C - #define vs const vs static

Question

Hi,

What is the best way to define a globally accessible string?

I see that for integer it's usually like this #define easy 0

However, how can I emulate that for NSString?
I tried static NSString *BACKGROUND = @"bg.png";
While that work, it does give a warning saying the variable is never used. (I have all these in a .h file)

Doing NSString *const BACKGROUND = @"bg.png"; is even worse since it says duplicate variable when I import the file.

I see that #define BACKGROUND @"bg.png" seems to work too.

So I guess what is the difference between when to use #define, const & static

Thanks,
Tee

Answer 1

This is the correct way to do it. Make some new blank .h file and .m. In your .h file:

extern NSString* const BACKGROUND;

In your .m file:

NSString* const BACKGROUND = @"bg.png";

Answer 2

You might want to consider using a property list to store your strings. This lets your code stay flexible for future updates, especially if you add support for localization.