Doxygen/Objective-C : how can I make constants that are declared outside the class definition show up in the class docs?

I'm using Doxygen to document some Objective-C code. I have some constants declared outside the class definition. I want these to show up in the class docs. How can I make doxygen include them? (Using \file just shows them in a separate documentation page).

#import blah blah

/**
 * This is my constant
 */
extern NSString*开发者_C百科constant someConstant; 

/**
 * More documentation
 */
@interface MyClass : NSObject <NSCoding> {

 //etc
}

Try to use the \memberof doxygen command. See.

#import blah blah

/**
 * \memberof MyClass
 * This is my constant
 */
extern NSString*constant someConstant; 

/**
 * More documentation
 */
@interface MyClass : NSObject <NSCoding> {

 //etc
}