ios - AFHTTPRequestOperationが完了したときに関数を実行する方法は?

Question

私はたくさん検索していくつかの答えを見ましたが、それを解決する方法はまだわかりません.操作が完了したときにのみ、void関数を実行したい.

私のコード:

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    [request setHTTPBody:[soapBody dataUsingEncoding:NSUTF8StringEncoding]];
    [request addValue:@"text/xml; charset=utf-8" forHTTPHeaderField:@"Content-Type"];
    [request setHTTPMethod:@"POST"];
    [request addValue:kAPP_PASSWORD_VALUE forHTTPHeaderField:kAPP_PASSWORD_HEADER];
    [request addValue:@"http://blablabla" forHTTPHeaderField:@"SOAPAction"];


    AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];

    [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
        self.responseXML = [operation responseString];        

        NSData *data = [self.responseXML dataUsingEncoding:NSUTF8StringEncoding];
        [self doParse:data];
        self.numOfWallPosts = [self.sharedPrefs integerForKey:@"total_number_of_wall_posts"];

        for (int i = 1; i <= self.numOfWallPosts; i++)
        {
            NSString *sharedKey = [NSString stringWithFormat:@"wall_number_%d", i];
            NSMutableDictionary *aaa = [[NSMutableDictionary alloc] init];
            aaa = [self.sharedPrefs objectForKey:sharedKey];
            [self handleWallPostsWithWallPost:aaa];
        }
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        NSLog(@"\n\nError: %@", error);
    }];

    [operation start];

[self handleWallPostsWithWallPost:aaa];- バックグラウンドでいくつかの画像をダウンロードしているため、ブロックは完了していますが、バックグラウンドでいくつかの画像がダウンロードされています。画像のダウンロードがいつ完了したかを知るにはどうすればよいですか?

- (void)handleWallPostsWithWallPost:(NSMutableDictionary *)wallPost
{
    NSMutableDictionary *temp = [[NSMutableDictionary alloc] init];
    temp = wallPost;

    NSString *owner = [temp objectForKey:@"owner"];
    NSString *title = [temp objectForKey:@"title"];
    NSString *imageUrl = [temp objectForKey:@"image_url"];
    NSInteger wallId = [[temp objectForKey:@"wall_id"] integerValue];
    NSLog(@"Wall ID: %d | Owner: %@ | Title: %@ | Image URL: %@", wallId, owner, title, imageUrl);

//    arrayOfOwnersImage - Save as NSData

    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:imageUrl]];
    AFImageRequestOperation *operation;
    operation = [AFImageRequestOperation imageRequestOperationWithRequest:request imageProcessingBlock:nil success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {
        NSLog(@"Image downloaded...");
        NSData *imageData = UIImageJPEGRepresentation(image, 90);
        [self.arrayOfOwnersImage addObject:imageData];
    } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {
        NSLog(@"Image download fail: %@", [error localizedDescription]);
    }];

    [operation start];
}

何か案は？