CODEWITHSUNDEEP
iosdownloadnsurlsessionnsurlsessiondownloadtask
André Maia
André Maia

Reputation: 51

NSURLSessionDownloadTask Delegates not calling didWriteData method

I'm starting to implement a download method using NSURLSession and successfully downloaded different files from multiple request. But now I wanted to add a progress track, however the delegates for download progress is not being triggered.

Here is my code:

NSURLSessionConfiguration *defaultConfigObject = NSURLSessionConfiguration defaultSessionConfiguration];

NSURLSession *defaultSession = [NSURLSession sessionWithConfiguration: defaultConfigObject delegate:self delegateQueue:nil];

NSURLSessionDownloadTask * downloadTask = [defaultSession downloadTaskWithRequest:request completionHandler:^(NSURL * __nullable location,
                                                                 NSURLResponse * __nullable response, NSError * __nullable error) {

NSData *data = [NSData dataWithContentsOfURL:location];

[[NSFileManager defaultManager] createFileAtPath:docPath contents:data attributes:nil];

if ([[NSFileManager defaultManager] fileExistsAtPath:docPath]) {

NSDictionary *notificationDic = [[NSDictionary alloc] initWithObjectsAndKeys:docPath,@"docPath", item, @"item", nil];

[[NSNotificationCenter defaultCenter] postNotificationName: @"openFile" object:nil userInfo:notificationDic];

}

}];
[downloadTask resume];

I have the NSURLSessionDownloadDelegate on my header file.

I needed to use completion handler to be able to perform different tasks with the file.

Is there a way I can do it?

Upvotes: 1

Views: 1998

Answers (3)

Iosif
Iosif

Reputation: 377

In my case the problem was I conform my class with URLSessionDelegate instead of URLSessionDownloadDelegate. Even if I was implementing the URLSessionDownloadDelegate methods.

Upvotes: 0

cbiggin
cbiggin

Reputation: 2142

You will have to initiate your download with:

- (NSURLSessionDownloadTask *)downloadTaskWithURL:(NSURL *)url;

And implement the delegate method for your progress:

- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
                                       didWriteData:(int64_t)bytesWritten
                                  totalBytesWritten:(int64_t)totalBytesWritten
                          totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite;

And since you need to perform various tasks when finished, you should also implement this delegate method:

- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
                          didFinishDownloadingToURL:(NSURL *)location;

Essentially, the completion handler routines are "convenience" routines to quickly perform the task and then when finished, perform the completion handler. But they don't call the other delegate routines.

Upvotes: 1

Rob
Rob

Reputation: 437422

If you use downloadTaskWithRequest rendition without the completionHandler parameter, then the progress delegate methods will be called. Obviously, you'll have to move the code currently in the completionHandler block into the didFinishDownloadingToURL method. But if you do this, you'll see didWriteData called.

Upvotes: 3

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