AFNetworking 2.0下载完成后的多个图像 [英] AFNetworking 2.0 download multiple images with completion

问题描述

我正试图找出一种使用AFNewtorking 2.0下载多张图像的方法。我在这里看了很多帖子，但是找不到我想要的答案，希望你们能帮助我。

I'm trying to figure out a way to download multiple images with AFNewtorking 2.0. I've read a lot of posts here in SO, but can't find the answer I'm looking for, hope you guys can help me.

问题是我希望知道所有下载完成后以及所有下载的图像。
所以我有一个图像URL蚂蚁的数组试图做这样的事情。

The problem is that I want to know when all of the downloads finished and if all images where downloaded. So I have an array with image URL's ant trying to do something like this.

for(NSString *photoUrlString in self.photos){

        NSURL *url = [NSURL URLWithString:photoUrlString];
        AFHTTPRequestOperation *requestOperation = [[AFHTTPRequestOperation alloc] initWithRequest:[NSURLRequest requestWithURL:url]];
        requestOperation.responseSerializer = [AFImageResponseSerializer serializer];
        [requestOperation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {

        } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
            NSLog(@"Image error: %@", error);
        }];
        [requestOperation start];
    }

我已经找到了一些答案，将这些请求放入队列并设置最大值并发操作为1.但不知道它是如何工作的。

I've found some answers with putting these requests into a queue and setting max concurrent operations to 1. But don't know how that works really.

感谢任何帮助，提前感谢！

Any help is appreciated, thanks in advance!

推荐答案

for(Photo *photo in array){

    //form the path where you want to save your downloaded image to
    NSString *constPath = [photo imageFullPath];

    //url of your photo
    NSURL *url = [NSURL URLWithString:photo.serverPath];

    AFHTTPRequestOperation *op = [[AFHTTPRequestOperation alloc] initWithRequest:[NSURLRequest requestWithURL:url]];
    op.responseSerializer = [AFImageResponseSerializer serializer];

    op.outputStream = [NSOutputStream outputStreamToFileAtPath:constPath append:NO];
    op.queuePriority = NSOperationQueuePriorityLow;
    [op setDownloadProgressBlock:^(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead){

    }];

    op.completionBlock = ^{

        //do whatever you want with the downloaded photo, it is stored in the path you create in constPath
    };
    [requestArray addObject:op];
}

NSArray *batches = [AFURLConnectionOperation batchOfRequestOperations:requestArray progressBlock:^(NSUInteger numberOfFinishedOperations, NSUInteger totalNumberOfOperations) {
} completionBlock:^(NSArray *operations) {

    //after all operations are completed this block is called
    if (successBlock)
        successBlock();
}];

[[NSOperationQueue mainQueue] addOperations:batches waitUntilFinished:NO];

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