iOS 5从AppDelegate打开特定的ViewController

Question

I am really new to IOS so I apologize if this questions is not worded clearly. I have tried searching around but I have not found exactly what I am looking for.

basically in my AppDelegate applicationDidBecomeActive method, I am making a call to my webservice to make sure that the user is still a valid user, and to pull down some refrehsed data, or kick them back to the login page if they are no longer valid.

The part that I am having trouble with is the second part. How can I load and show and specific ViewController(in this case the loginViewController) when the user is found to be invalid? I want to let the normal viewController flow happen when they are valid, which is is doing fine, but I can not figure out how to launch a specific viewController when I need to from AppDelegate.

Any ideas?

I think I got it! I used this code in the AppDelegate to display the ViewController I needed.

UIViewController *loginController = [self.window.rootViewController.storyboard instantiateViewControllerWithIdentifier:@"LoginViewController"];
    UINavigationController *loginNavController = [self.window.rootViewController.storyboard instantiateViewControllerWithIdentifier:@"LoginNavController"];
    UIViewController *currentVC = self.window.rootViewController;
    _window.rootViewController = loginNavController;
    [currentVC presentViewController:loginNavController animated:NO completion:nil];

Answer 1

For simplicity, lets say you have a one view app (not nav controller, not tab bar controller - the solution scales but easier to explain). When you get the appDelegate message that the app launched, then make a UIImageView the root view and show your launch image (user thinks you are still booting up). Try to log in, and do this in some other object (not a view controller). If you succeed, you make your desired view the rootView, and users sees it. If the login fails, then you makea login window the rootView. The key here is to have an object that is driving this and can interact with the appDelegate. You could also add this functionality to the appDelegate itself.