Showing the file download progress with NSURLSessionDataTask

Question

I want to display file download progress (how many bytes are received) of particular file. It works fine with the NSURLSessionDownloadTask .My question is I want to achieve the same with the NSURLSessionDataTask.

Here is the code which receives file into NSData and writes to document folder:

NSURLSessionConfiguration *defaultConfigObject = [NSURLSessionConfiguration defaultSessionConfiguration];

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

NSURLSessionDataTask * dataTask = [defaultSession dataTaskWithURL:theRessourcesURL
    completionHandler:^(NSData *data, NSURLResponse *response, NSError *error)
{ 
       if(error == nil)
       {

            NSString *docsDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];

               NSString *pathToDownloadTo = [NSString stringWithFormat:@"%@/%@", docsDir, Name];

               NSLog(@"SIZE : %@",[NSByteCountFormatter stringFromByteCount:data.length countStyle:NSByteCountFormatterCountStyleFile]);

               [data writeToFile:pathToDownloadTo options:NSDataWritingAtomic error:&error];
       }
}];

[dataTask resume];

I am getting file size after write or complete datatask (after the file is received) :

NSLog(@"SIZE : %@",[NSByteCountFormatter stringFromByteCount:data.length countStyle:NSByteCountFormatterCountStyleFile]);

But i want to display it's current bytes received status, is this possible with NSURLSessionDataTask?

Answer 1

You need to implement following delegates:

<NSURLSessionDataDelegate, NSURLSessionDelegate, NSURLSessionTaskDelegate>

Also need to create two properties:

@property (nonatomic, retain) NSMutableData *dataToDownload;
@property (nonatomic) float downloadSize;

- (void)viewDidLoad {
    [super viewDidLoad];

    NSURLSessionConfiguration *defaultConfigObject = [NSURLSessionConfiguration defaultSessionConfiguration];

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

    NSURL *url = [NSURL URLWithString: @"your url"];
    NSURLSessionDataTask *dataTask = [defaultSession dataTaskWithURL: url];

    [dataTask resume];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition disposition))completionHandler {
    completionHandler(NSURLSessionResponseAllow);

    progressBar.progress=0.0f;
    _downloadSize=[response expectedContentLength];
    _dataToDownload=[[NSMutableData alloc]init];
}

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data {
    [_dataToDownload appendData:data];
    progressBar.progress=[ _dataToDownload length ]/_downloadSize;
}