gistfile1.txt

+ (NSString *)hashForObject:(id)object usingMethod:(AJCHasherMethod)method {
    //object = [object copy];
    
    CC_MD5_CTX context;
    CC_MD5_Init(&context);
    
    if ([object respondsToSelector:@selector(countByEnumeratingWithState:objects:count:)]) {
        if([object isKindOfClass:[NSDictionary class]]) {
            // It's an NSDictionary, need to hash the keys and values seperately, combine them, then reorder them into an array.
            NSMutableArray *newArray = [NSMutableArray new];
            for (id subObject in  [object sortedArrayUsingSelector:@selector(compare:)) {
                NSString *hashedKey = [self hashForObject:subObject usingMethod:method];
                CC_MD5_Update ( hashedKey );
                
                NSString *hashedObject = [self hashForObject:object[subObject] usingMethod:method];
                CC_MD5_Update ( hashedObject  );
            }
                                   
        }
        
        if([object isKindOfClass:[NSOrderedSet class]]) {
            // Make this NSSet into an array.
            object = [object array];
        }
        
        if([object isKindOfClass:[NSArray class]]) {
            for (id subObject in object) {
                CC_MD5_Update ( [self hashForObject:subObject usingMethod:method]  );
            }
            
        } else if([object isKindOfClass:[NSSet class]]) {
            for (id subObject in [object sortedArrayUsingSelector:@selector(compare:)) {
                CC_MD5_Update ( [self hashForObject:subObject usingMethod:method]  );
            }
        }
    } else if ([object isKindOfClass: [NSString class]]) {
        CC_MD5_Update ( string contents  );
    } else {
        // Unknow object, used keyed archiver to hash ?
        NSData *data = [NSKeyedArchiver archivedDataWithRootObject:object];
        CC_MD5_Update ( data  );
    }

    unsigned char result[CC_MD5_DIGEST_LENGTH];
    CC_MD5_Final(result, &context);                                      

  NSMutableString *output = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH * 2];
  for(int i = 0; i < 15; i++) {
      [output appendFormat:@"%02x", result[i]];
  }
  return output;
}