How can I receive my data in pieces with using NSURLConnection's sendAsynchronousRequest method?

Question

When I send a synchronous request with NSURLConncetion

[NSURLConnection initWithRequest:myRequest delegate:self];

I can receive my downloaded data in pieces with the following method

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {

    [self.videoData appendData:data];
    NSLog(@"APPENDING DATA %@",data);

}

The advantage of this is that I can write my data directly to a file, and limit ram usage when downloading large files.

When I send an asynchronous request, how can I receive my data in pieces? The only place I see the data given back to me is in the completion handler of the request.

 [NSURLConnection sendAsynchronousRequest:videoRequest 
                                    queue:downloadQueue 
                        completionHandler:^(NSURLResponse* response, NSData* data, NSError* error){
        NSLog(@"All data is given here!");
    }];

Is there any solution to this problem? I'm downloading large files in a view controller and want to continue downloading them if the view controller gets dismissed. The problem is that I'm going to use too much memory if I receive all my data at once when downloading large files.

Surrealism

Why do you think you need to use sendAsynchronousRequest? Why not continue with NSURLConnection and delegate methods if that works? – Kingsly

When I dismiss my view controller my connection dies. What can I do about that? – Surrealism

Keep a pointer to it in the controller that presented it. – Kingsly

Answer 1

The only method in NSURLConnection which is synchronous is + sendSynchronousRequest:returningResponse:error:

The following methods are all asynchronous

+ connectionWithRequest:delegate:
– initWithRequest:delegate:
– initWithRequest:delegate:startImmediately:
+ sendAsynchronousRequest:queue:completionHandler:
– start

So the code [NSURLConnection initWithRequest:myRequest delegate:self]; itself is an asynchronous, You can use it as it is.

OR

You can make use of NSURLSession for more control

NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:nil];

self.downloadTask = [self.session downloadTaskWithRequest:request];
[self.downloadTask resume];

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

}

Cadet

Ignore my previous comment, my connection dies when the view controller it is launched in is dismissed. What can I do? – Surrealism

Its better to make a shared object which always keep track of you download data till app is running irrespective of view controller. – Cadet