CODEWITHSUNDEEP
iosobjective-cmultithreading
TooManyEduardos
TooManyEduardos

Reputation: 4394

NSURLSession delegates on UI thread with NSOperation

I got challenged to use the NSURLSession delegates to update a UI element (just a label) with the status of the download, but I can only use NSOperation and not dispatch_get_main_queue

I'm not even sure this is possible to call the UI thread with NSOperation directly (and not a completion block), but I thought of ask here to see if anyone knows if this is possible.

In a nutshell, this is what I have with the C calls to dispatch_async:

- (void)URLSession:(NSURLSession *)session
      downloadTask:(NSURLSessionDownloadTask *)downloadTask
      didWriteData:(int64_t)bytesWritten
 totalBytesWritten:(int64_t)totalBytesWritten
totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite
{
    long percentage = (totalBytesWritten * 100) / totalBytesExpectedToWrite;

    dispatch_async(dispatch_get_main_queue(),
       ^{
           self.label_bytesExpected.text = [NSString stringWithFormat:@"Expected = %lld", totalBytesExpectedToWrite];
           self.label_bytesWritten.text = [NSString stringWithFormat:@"Received = %lld (%ld%%)", totalBytesWritten, percentage];
       });
}

Is it possible to call NSOperation (queue or block or anything else with it) to display this on the UI instead of using dispatch_async(dispatch_get_main_queue(), block)?

Thank you!

Upvotes: 1

Views: 382

Answers (2)

Maciej Oczko
Maciej Oczko

Reputation: 1225

NSURLSession has a property called delegateQueue which indicates on which queue delegate's methods will be called. It can be set to [NSOperationQueue mainQueue] via factory method: [NSURLSession sessionWithConfiguration:configuration delegate:delegate delegateQueue:[NSOperationQueue mainQueue]];

Upvotes: 0

Avt
Avt

Reputation: 17043

Yes. It is possible. You should use [NSOperationQueue mainQueue]

+ (NSOperationQueue *)mainQueue

Returns the operation queue associated with the main thread.

So your code could be:

[[NSOperationQueue mainQueue] addOperationWithBlock:^{
        self.label_bytesExpected.text = [NSString stringWithFormat:@"Expected = %lld", totalBytesExpectedToWrite];
        self.label_bytesWritten.text = [NSString stringWithFormat:@"Received = %lld (%ld%%)", totalBytesWritten, percentage];
    }];

Upvotes: 2

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