How to configure app so that root view controller is found? - objective-c

Question

I am new and am working on an exercise which involves starting with a navigation-based template. Since I am running Xcode 4.2 which no longer has that template, I have started with an empty application template, and then copied the directory structure of the completed app.
Since the empty app template starts only with an AppDelegate.h, .m files, I started adding other required files, including the MainWindow.xib, and the RootViewController.h, .m files. Did some tweaking of the #import directive so that it could see the right files, and could start alright.
However, when I try to run it on the iOS Simulator, I got this message: Applications are expected to have a root view controller at the end of application launch
Terminating in response to SpringBoard's termination.
Program ended with exit code: 0
What additional changes do I need to make so that the app can see the RootViewController?
Thank you.

Answer 1

In -[AppDelegate application:didFinishLaunchingWithOptions:], you need to set your window's rootViewController property.

Answer 2

You need to set the rootViewController property of AppDelegate's _window:
- (BOOL)application:(UIApplication *)application
didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
_window.rootViewController = self.myNavigationController;
[_window makeKeyAndVisible];
return YES;
}
To start a traditional navigation-based project in XCode 4.2, I find it easier to start with the single-view template. Then, in AppDelegate, I substitute the generated UIViewController with a UINavigationController.

Answer 3

self.window.rootViewController=self.yourviewControollerobj

Answer 4

You can set like this. First set the window bounds then add you navigation controller with root view controller.
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
self.window = [[UIWindow alloc]initWithFrame:[[UIScreen mainScreen]bounds]];
MainViewController *vc = [MainViewController new];
/*
* If you are using .xib you should create UIViewontroller like this
* MainViewController *vc = [MainViewController alloc] initWithNibName:#"MainViewController" bundle:nil]
*/
UINavigationController *nc = [[UINavigationController alloc] initWithRootViewController:vc];
[self.window setRootViewController:self.nc];
[self.window makeKeyAndVisible];
return YES;
}

Answer 5

MyViewController *rootCtr = [[MyViewController alloc] init];
[rootCtr.view addSubview:myView];
window.rootViewController = rootCtr;