NSURLSession委托didCompleteWithError不被调用

Question

I have the below implementation of NSURLSession .

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

NSURLSessionDataTask *task = [self.session dataTaskWithRequest:request];
[task resume];        
while(!finished) {
    [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate dateWithTimeIntervalSinceNow:100000]];
}  

and i have implemented the below delegate methds:

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data  
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)aresponse  
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didCompleteWithError:(NSError *)error  
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge 
  completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition disposition,
                         NSURLCredential *credential))completionHandler  

the "finished" variable for while loop above is set to 1 when didCompleteWithError delegate is received when indicates that there is some issue like network down, etc...

When network is down, i don't get didCompleteWithErrorcallback , hence the while loop does not exit even though 10sec timeout has been specified and my app crashes giving Memory warning .

I do properly receive didReceiveData, didReceiveResponse callback in all scenarious .have not checked didReceiveChallenge callback though as it requires HTTPs setup here.

so , i have following questions to ask , if you can help me :

1)Why is didCompleteWithError callback not received when network is down?

2)Considering no network issues ,is didCompleteWithError callback received on successful completion of task ?If no, what callback would indicate the completion of task , like connectionDidFinishLoading when using NSURLConnection ?

I have used cachepolicy in the request parameter while starting task. Is it because of this that didcompletewitherror is not called n instead caching delegate should be implemented??

Guys, Please help. I am stuck.

Thankyou

Answer 1

delegateQueue :[NSOperationQueue mainQueue] instead of instead of delegateQueue :nil did the trick . I am still not sure how. But yes, the issue is gone. could anybody explain how this worked ?

Answer 2

Your loop "while(!finished)" is really bad practice. Basically the download task is async operation however with your while-loop you are blocking the thread and force the download task to finish in that thread. This might impact system behavior.

I belive removing this loop will solve your problem.