IOS RestKit, how to send a request using a callback object (userData)?

I am trying to create a RestKit request to download an image from a web service and add it to a button as a background image . To do this asynchronously, I am trying to add a button as userData to the RKRequest object.

I'm not sure how to send a fully configured RKRequest, I tried to set delegate

by calling prepareURLRequest

and sendAsynchronously

. The method that I expect to be called is not called.

- (void)didFinishLoad:(RKResponse*)response

      

        
        
        
      

    

To test if my request was configured correctly, I sent it through the request queue and it works.

What is the correct way to send fully customized requests using the userData object using RestKit?

- (void)sendRequestForTrackerUserGravatar:(CoreDataButton*)coreDataButton {

      

        
        
        
      

    

/ * This works, but doesn't allow setting the user data object, i.e. I don't know which button image was loaded.

    NSMutableDictionary* paramsDictionary = [[NSMutableDictionary alloc] init];   
    [paramsDictionary setValue:@"identicon" forKey:@"d"];

      

        
        
        
      

    

[[RKClient sharedClient] get: [self gravatarMD5HashWithUserID: trackerUser.user_id.intValue] queryParams: paramsDictionary delegate: self];
* /

    //single request for a resource, includes a dictionary of parameters to be appended to the URL
    //    [paramsDictionary setValue:@"retro" forKey:@"d"];
    User* user = (User*)coreDataButton.managedObject;


    NSString* md5Hash = [self gravatarMD5HashWithUserID:user.user_id.intValue];
    NSString* urlString = [NSString stringWithFormat:@"%@%@?d=identicon",kGravatarWebsite,md5Hash];
    RKRequest* request = [[RKRequest alloc] initWithURL:[NSURL URLWithString:urlString] delegate:self];
    request.userData = coreDataButton;
    request.delegate = self;   
    request.cachePolicy = RKRequestCachePolicyEnabled;

//this works    
//[[RKRequestQueue sharedQueue] addRequest:request];


//this does not seem to call back the delegate method    
    [request prepareURLRequest];
    [request sendAsynchronously];

    }

//request callback, does not get called
- (void)didFinishLoad:(RKResponse*)response
{
    [self processResponse:response];
}

//queue callback, DOES get called
-(void)requestQueue:(RKRequestQueue *)queue didLoadResponse:(RKResponse *)response
{
    [self processResponse:response];
}