How to use [diagnostic pragmas][1] to annotate a class/method so as to show a message on compile. [1]: http://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Pragmas.html PS. Tested on XCode 4.6.1 http://i.minus.com/iepXiFcByxuKt.png

gistfile1.m

#define DO_PRAGMA(x) _Pragma (#x)
#define MESSAGE(x) DO_PRAGMA(message (x))
 
@interface TBFoo : NSObject
@end
 
@implementation TBFoo
 
-(void)bar MESSAGE("Hello World!"){}

@end