gistfile1.cpp

/** 
 * Link against MobileGestalt
 */

OBJC_EXTERN CFStringRef MGCopyAnswer(CFStringRef property) WEAK_IMPORT_ATTRIBUTE;

void someFunction() {
    CFStringRef udid = MGCopyAnswer(CFSTR("UniqueDeviceID"));

    /*
        Do stuff with it
    */

    CFRelease(udid);    
}