iOS - Twitter upload image with SLRequest

gistfile1.txt

/**
 *  Upload an image to twitter to get media_id for is
 *
 *  @param img        The image (UIImage or NSData) to be uploaded
 *  @param completion
 */
- (void)sendTweetWithImage:(id)img withCompletion:(void(^)(NSNumber *mediaID, NSError *error))completion {
    
    NSURL *requestURL = [[NSURL alloc] initWithString:@"https://upload.twitter.com/1.1/media/upload.json"];

    //Get image data
    NSData *data = img;
    if ([img isKindOfClass:[UIImage class]]) {
        data = UIImagePNGRepresentation(img);
    }
    
    ACAccount *twitterAccount = [self.accounts objectAtIndex:0];
   
    SLRequest *postRequest = [SLRequest
                              requestForServiceType:SLServiceTypeTwitter
                              requestMethod:SLRequestMethodPOST
                              URL:requestURL parameters:nil];

    //Setup upload TW request
    [postRequest addMultipartData:data withName:@"media" type:@"image/png" filename:@"image.png"];
    
    postRequest.account = twitterAccount;
    
    //Post the request to get the media ID
    [postRequest performRequestWithHandler:
     ^(NSData *responseData, NSHTTPURLResponse *urlResponse, NSError *error)
     {
         if (!error && responseData) {
             
             NSString *resp = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
             DLog(@"restp : %@",resp);
             if (error) {
                 NSLog(@"error :%@",error);
             }
             NSError *jsonError = nil;
             NSDictionary *json = [NSJSONSerialization JSONObjectWithData:responseData options:0 error:&jsonError];
             
             if (jsonError) {
                 error = jsonError;
             }
             
             if (completion) {
                 completion(json[@"media_id"],error);
             }
         }
         else {
             if (completion) {
                 completion(nil,error);
             }
             
         }
     }];
}