Core data and TabViewController

Question

In my project I'm using a tabBarController, then on one of my tabs, I add a navigation controller.

The problem I'm having is this: If I use this code in the AppDelegate:

• (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

  // Override point for customization after application launch

  [window addSubview:[rootController view]];

  [window makeKeyAndVisible];

  return YES; } my tabBar view (which is in the main.xib) comes up, but when I click on the tab for the navigation controller (which is using core data) the app crashes with this error:

NSInternalInconsistencyException', reason: '+entityForName: could not locate an NSManagedObjectModel for entity name 'HotSprings

So, I found this code for the AppDelegate: - (void)applicationDidFinishLaunching:(UIApplication *)application {

NSManagedObjectContext *context = [self managedObjectContext];
if (!context) {
    // Handle the error.
}

RootViewController *rootViewController = (RootViewController *)[navController topViewController];
rootViewController.managedObjectContext = self.managedObjectContext;

[window addSubview:[navController view]];
[window makeKeyAndVisible];

} But, of course, it loads the navigation controller view and ignores main.xib and the tab bar controller.

So, I need to know how to use this last code, but load the tab bar and main.xib. I tried changing the navController to my rootController (which is my tabBarController property, but it doesn't like the "topViewController", which is associated with the navigation controller.

Thanks, Jaime