Example of how to use the category key/value approach from my blogpost here: http://appventure.me/2011/12/fast-nsdictionary-traversal-in-objective-c.html

gistfile1.m

#import <Cocoa/Cocoa.h>

@interface NSDictionary (objectForKeyList)
- (id)objectForKeyList:(id)key, ...;
@end

@implementation NSDictionary (objectForKeyList)

- (id)objectForKeyList:(id)key, ...
{
  id object = self;
  va_list ap;
  va_start(ap, key);
  for ( ; key; key = va_arg(ap, id))
      object = [object objectForKey:key];
  
  va_end(ap);
  return object;
}
@end

int main() {
  NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
  
  NSDictionary *aDictionary = [NSDictionary dictionaryWithObject:
     [NSDictionary dictionaryWithObject:
       [NSDictionary dictionaryWithObject:
         [NSDictionary dictionaryWithObject: @"Magnus Enzensberger" forKey:@"friend"]
       forKey: @"data"]
      forKey: @"likes"]
     forKey: @"data"];
     
   NSLog(@"%@", [aDictionary objectForKeyList: @"data", @"likes", @"data", @"friend", nil]);
  
  [pool release];
  return 1;
}