Does NSURLConnection Block the Main/UI Thread

Question

I am downloading images in table view cells as they scroll onto the screen. For UX reasons, I start downloading the images in - (UITableViewCell *)tableView:(UITableVi

Answer 1

Read NSDefaultRunLoopMode vs NSRunLoopCommonModes for a good explanation of why all the download delegate notifications are queued up, but to download while scrolling when using the main thread change from this:

NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request
                                                              delegate:self];

to this:

NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request
                                                              delegate:self
                                                      startImmediately:NO];
[connection scheduleInRunLoop:[NSRunLoop currentRunLoop]
                      forMode:NSRunLoopCommonModes];
[connection start];