bycopy-1.m

this is a gcc file, you can download it and learn its usetility, for further detail please look at t

/*
 * Contributed by Nicola Pero <[e-mail]>
 * Fri Feb  2 11:48:01 GMT 2001
 */

#include <objc/objc.h>
#include <objc/Protocol.h>

@protocol MyProtocol
- (bycopy id) bycopyMethod;
@end

int main (void)
{
  [nil bycopyMethod];

   exit (0);
}