NSURLConnection sendSynchronousRequest seems to hang

Question

This HTTP call seems to be hanging and I can't see why. The logging line after the call never runs.

I'm almost certainly doing something extremely stupid, but if anyone can spot what it is I'd be grateful. As far as I can see my code is equivalent to the docs.

It doesn't seem to matter what URL I use, and the HTTP request is never logged by the server (if pointed at one).

NSURLRequest *req = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.google.com/"]];

NSURLResponse *res = nil;
NSError *err = nil;

NSLog(@"About to send req %@",req.URL);

NSData *data = [NSURLConnection sendSynchronousRequest:req returningResponse:&res error:&err];

NSLog(@"this never runs");

Any ideas?

Update

Thanks to everyone who's posted so far. Still seeing the problem. A bit more detail:

• The code is being tested on the device
• Other HTTP calls work fine so if it's a network problem it's a non-trivial one
• The code has hung well past the normal timeout. I know it hangs for over 20 minutes. I killed it at that point, but I assume it would continue to hang.
• I'm not currently using a delegate and don't plan to, see below.
• In other places in the app I use sendAynchronousRequest but in this instance I need to pass a return value (and I'm not on the main thread), so sendSynchronousRequest is the only option I know of.
• In case it matters, the context is that I'm implementing the NSURLCache protocol, specifically the cachedResponseForRequest method, which requires I return a NSCachedURLResponse

Answer 1

Run the request in a background queue so it does not block the main thread where UI updates occur:

 dispatch_queue_t myQueue = dispatch_queue_create("myQueue", NULL);

    // execute a task on that queue asynchronously
    dispatch_async(myQueue, ^{
NSURLRequest *req = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.google.com/"]];

NSURLResponse *res = nil;
NSError *err = nil;

NSLog(@"About to send req %@",req.URL);

NSData *data = [NSURLConnection sendSynchronousRequest:req returningResponse:&res error:&err];

    });

Answer 2

Add delegate <NSURLConnectionDataDelegate>

NSURL *url = [[NSURL alloc]initWithString:[NSString stringWithFormat:@"Your string here"];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    NSURLConnection *connection = [NSURLConnection connectionWithRequest:request delegate:self];
    [connection start];//It will start delegates


-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    [received_data setLength:0];//Set your data to 0 to clear your buffer 
}

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

    [received_data appendData:data];//Append the download data..
}

-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    //Use your downloaded data here
}

This method more better to download data.. It wont use main thread so the app wont hang.. I hope it will be more useful for you