Question

I have set up some constants in my Xcode project using the advice in this question, and it works just fine. Now, however, I would like to set a different value for two of these constants depending on whether it’s an iPad or iPhone.

Here’s my Constants.h file:

extern integer_t const kFontSize;
extern integer_t const kFontSizeMicro;

and my .m:

integer_t const kFontSize = 16;
integer_t const kFontSizeMicro = 11;

Now I would like to change those values depending on a #define macro setup in my .pch file. But this doesn’t work:

if (IS_IPAD) {
    integer_t const kFontSize = 25;
    integer_t const kFontSizeMicro = 15;
}

The error I get is “Expected identifier or (” on the “if”.

Anyone know how to allow the conditional statement in this case?

Answer 1

The if statement of the C language cannot be used outside a function body to control a global declaration like that. You can use the preprocessor’s #if instead:

#if (IS_IPAD)
    integer_t const kFontSize = 25;
    integer_t const kFontSizeMicro = 15;
#else
    integer_t const kFontSize = 20;
    integer_t const kFontSizeMicro = 12;
#endif

This is not too different from using #define-d constants, though. If you would like to make the constants settable at runtime, – say, during initialization, – you will need to drop const from the declarations, and put the regular if into an initialization function – for example, the application:didFinishLaunchingWithOptions:.