Make a class sub-scriptable

gistfile1.m

/*
  Define the proper methods based on the 
  desired kind of subscripting, indexed
  or keyed
*/

@interface IndexedSubscriptable
- (id)objectAtIndexedSubscript:(NSUInteger)idx
- (void)setObject:(id)anObject atIndexedSubscript:(NSUInteger)index
@end

@interface KeyedSubscriptable
- (id)objectForKeyedSubscript:(id)key
- (void)setObject:(id)object forKeyedSubscript:(id < NSCopying >)aKey
@end