Xcode -- have a macro behave differently depending on whether it is included from a .h file or a .m file?

I want to have a macro SomeMacro(city, country) in a file that will be in a file MacroFile.h that I will #include from either a .h file or a .m file. And I want SomeMacro to become something different depending on whether the file immediately above MacroFile.h in the include tree is a .h file or a .m file. I want to do this without defining a special constant in the .m file. Is that possible?

In pseudo-code, what I want MacroFile.h to do is this:

#if (file from which I was directly included is a .h)
#define SomeMacro(city, country) SomeStuffInvolvingCityAndCountry
#else
#define SomeMacro(city, co开发者_开发问答untry) SomeDifferentStuffInvolvingCityAndCountry
#endif

SomeMacro(washington, USA)
SomeMacro(tokyo, Japan)
SomeMacro(berlin, Germany)

Bonus points if you can also get MacroFile.h to examine what is two levels above it in the include tree.

EDIT: If there is a way for the macro to tell whether or not it is being called from inside an @implementation block, that would be good enough.

There is no preprocessor test to determine where the macro is being expanded from. .h is a convention for a header file, but has no semantic value.

You could create two files MacroFile-header.h and MacroFile-code.h as follows:

MacroFile-header.h:

// definitions
#define CityCountryMacro(city, country)  SomeStuffInvolvingCityAndCountry
#define StateZipMacro(state, zip)        SomeStuffInvolvingStateAndZip

MacroFile-code.h:

// undefine MacroFile-header.h macros
#if defined(CityCountryMacro)
    #undef CityCountryMacro
#endif
#if defined(StateZipMacro)
    #undef StateZipMacro
#endif

// definitions
#define CityCountryMacro(city, country)  OtherStuffInvolvingCityAndCountry
#define StateZipMacro(state, zip)        OtherStuffInvolvingStateAndZip

Always import MacroFile-header.h in your header files, as follows:

SomeObject.h:

#import "MacroFile-header.h"

// use macros

and MacroFile-code.h after all other imports, in your implementation:

SomeObject.m:

#import "SomeObject.h"
#import ...
#import ...

// always include last
#import "MacroFile-code.h"

// use macros