How to set up a navigationController by UINavigationController? - iphone

Question

I am working with push notifications. i am trying to create and push a DetailView in the navigationController when action button in notification is clicked. but navigationController is nil. how can i put that DetailView in the navigationController? I want to push RootViewController in the navigationController and then the DetailView. how can i do that?
in AppDelegate:
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo {
RootViewController *controller = [[RootViewController alloc] init];
//getting warnings here.(Unused variable navigationController)
UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:controller];
[controller doStuff];
[controller release];
}
in RootViewController:
-(void)doStuff{
[[self stories] removeAllObjects];
[self startParsing];
[self.tableView reloadData];
DetailViewController *detail = [[DetailViewController alloc] init];
//custom code
[self.navigationController pushViewController:detail animated:YES];
[detail release];
this is the code i m using right now. and plz notice that i have
[self.tableView reloadData];

Answer 1

Okay, now I am pretty sure I understand the issue. The problem is, you never manually set the navigationController property on a UIViewController. The navigationController property is nil if the view controller is not under a navigation controller and if it is, then the property points to it.
What you need to do, is when you display your root view controller, instead of directly displaying its view, add it to a navigation controller, then display the navigation controller's view. Like so:
RootViewController *controller = [[RootViewController alloc] init];
UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:controller];
//Here you would display navigationController.view somehow
So, after you have your root view controller in a navigation controller, in a method in root view controller you can do this:
DetailViewController *detail = [[DetailViewController alloc] init];
//Do whatever you need to do to set values on the detail view controller
[self.navigationController pushViewController:detail animated:YES];
The key thing is this: you need to put the root view controller into a navigation controller before you can access a navigation controller from within root view controller.

Answer 2

If your nav controller is nil, it needs creating and then you place things into it.
Try this:
UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:rootViewController];
[navController pushViewController:detailViewController animated:NO]; // or YES

Answer 3

If you start out with no UINavigationController and want to display it with more than one view controller in its stack, after initing the navigation controller you can set the viewControllers property to an array with the various view controllers you want.
edit: some example code:
UINavigationController *navController = [[UINavigationController alloc] init];
NSArray *viewControllers = [NSArray arrayWithObjects:viewController1, viewController2, nil];
[navController setViewControllers:viewControllers animated:NO];
After doing that, your navigation controller will have viewController2 on top and viewController1 behind it.
Alternately, you could do it this way:
UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:viewController1];
[navController pushViewController:viewController2 animated:NO];