gistfile1.m

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, (unsigned long)NULL), ^{
        [self setClient:[[JJRemoteAssetClient alloc] init]];
        [self.client GET:[NSURL URLWithString:self.thumbURL]
                 success:^(AmazonServiceResponse *response) {
                     NSLog(@"Fetched thumbnail: %@", self.thumbURL);
                     [JJRemoteAssetClient saveImageWithData:response.body
                                                    andName:self.thumbName];
                 }
                 failure:^(NSError *error) {
                     NSLog(@"error: %@", error);
                 }];

    });