accessing the navigation controller from separate delegate class

I am follwing a tutorial from a book and there the delegate and datasource are separated from the controller (MyViewController.m)

[self setDataSource:[[MyViewDa开发者_开发问答taSource alloc]
[self setDelegate:[[MyViewDelegate alloc]

for understanding, I now want to pop a controller from the delegate class (MyViewDelegate.m)

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
        2ndViewController *controller = [[2ndViewController alloc]];
        [[self navController] pushViewController:controller animated:YES];

of course this will not work since the navcontroller sits in the app delegate. But how do I best access the navcontroller from the delegate class ?

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You can do something like

UINavigationController *navController = [(MyAppDelegate*)[[UIApplication sharedApplication] delegate] navigationController];

However, you should ask yourself why you need to do this and if there is a better way that is more in keeping with MVC (model view controller) and the rules of encapsulation.

For instance, UIViewController presents a property named navigationController, which, as explained by the documentation, will return the appropriate navigation controller for the given view controller.