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POHow to track progress of multiple simultaneous downloads with AFNetworking?
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  1. POHow to track progress of multiple simultaneous downloads with AFNetworking?
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    copied!<p>I am using AFNetworking to download files that my app uses for a sync solution. At certain times, the app downloads a series of files as a batch unit. <a href="https://stackoverflow.com/a/19883392/353137">Following this example</a>, I run the batch like this:</p> <pre><code>NSURL *baseURL = &lt;NSURL with the base of my server&gt;; AFHTTPRequestOperationManager *manager = [[AFHTTPRequestOperationManager alloc] initWithBaseURL:baseURL]; // as per: https://stackoverflow.com/a/19883392/353137 dispatch_group_t group = dispatch_group_create(); for (NSDictionary *changeSet in changeSets) { dispatch_group_enter(group); AFHTTPRequestOperation *operation = [manager POST:@"download" parameters: &lt;my download parameters&gt; success:^(AFHTTPRequestOperation *operation, id responseObject) { // handle download success... // ... dispatch_group_leave(group); } failure:^(AFHTTPRequestOperation *operation, NSError *error) { // handle failure... // ... dispatch_group_leave(group); }]; [operation start]; } // Here we wait for all the requests to finish dispatch_group_notify(group, dispatch_get_main_queue(), ^{ // run code when all files are downloaded }); </code></pre> <p>This works well for the batch downloads. However, I want to display to the user an MBProgressHUD which shows them how the downloads are coming along.</p> <p>AFNetworking provides a callback method</p> <pre><code>[operation setDownloadProgressBlock:^(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead) { }]; </code></pre> <p>... which lets you update a progress meter pretty easily, simply by setting the progress to <code>totalBytesRead / totalBytesExpectedToRead</code>. But when you have multiple downloads going simultaneously that is hard to keep track of on a total basis.</p> <p>I have considered having an <code>NSMutableDictionary</code> with a key for each HTTP operation, with this general format:</p> <pre><code>NSMutableArray *downloadProgress = [NSMutableArray arrayWithArray:@{ @"DownloadID1" : @{ @"totalBytesRead" : @0, @"totalBytesExpected" : @100000}, @"DownloadID2" : @{ @"totalBytesRead" : @0, @"totalBytesExpected" : @200000} }]; </code></pre> <p>As each operation's download progresses, I can update the <code>totalBytesRead</code> for that specific operation in the central <code>NSMutableDictionary</code> -- and then total up all the <code>totalBytesRead</code> and <code>totalBytesExpected' to come up with the total for the whole batched operation. However, AFNetworking's progress callback method</code>downloadProgressBlock<code>, defined as</code>^(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead){}<code>does not include the specific operation as a callback block variable (as opposed to the</code>success<code>and</code>failure` callbacks, which do contain the specific operation as a variable, making it accessible). Which makes it impossible, as far as I can tell, to determine which operation specifically is making the callback.</p> <p>Any suggestions on how to track the progress of multipole simultaneous downloads using AFNetworking?</p>
 

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