- (id) objectAtIndexedSubscript: ( NSUInteger ) idx ;- (void) setObject: ( id ) obj atIndexedSubscript: ( NSUInteger ) idx ;- (void) setObject: ( id ) obj forKeyedSubscript: ( id < NSCopying > ) key ;- (id) objectForKeyedSubscript: ( id ) key ;我找到的是这个帖子：http://petersteinberger.com/blog/2012/using-subscripting-with-Xcode-4_4-and-iOS-4_3/