Continue download in background

Programming for iPhone: Continue download in background on newest questions tagged iphone – Stack Overflow

I am creating an application wherein I am downloading some data from server. While going in background I want that connection should continue running so that data can be downloaded. I know there is method in appDelegate

- (void)applicationDidEnterBackground:(UIApplication *)application

which is called when application enters background. But as the connection is created in viewController, how can it be managed in appDelegate?
Also is/are there other way(s) this can be done? I have gone through this link but is there a something simple to implement?
Thanks,
Nitish

source: http://stackoverflow.com/questions/11100874/continue-download-in-background
Programming for iPhone: programming-for-iphone