iOS – uinavigationController – Application tries to push a NIL view controller on the target, what do I miss?

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:( NSIndexPath *)indexPath{

 UINavigationController *navigationController= [[UINavigationController alloc]init];

 switch ([indexPath row]) {

 case 0:
 [navigationController pushViewController:kundeViewCon animated:YES];
 break;

 case 1:
 [navigationController pushViewController:kalenderViewCon animated:YES];
 break;

 case 2:
 [navigationController pushViewController:wunschViewCon animated:YES];
 break;
} 
}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
 self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
 // Override point for customization after application launch.

// Navigation Controller

 RootViewController *rootViewController = [[RootViewController alloc]init];

 navigationController = [[UINavigationController alloc]initWithRootViewController:rootViewController];

 self.window.backgroundColor = [UIColor whiteColor] ;

 [self.window addSubview:navigationController.view];
 [self.window makeKeyAndVisible];
 return YES;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath: (NSIndexPath *)indexPath
{
 switch ([indexPath row]) {
 case 0:
 [self.navigationController pushViewController:kundeViewCon animated:YES];
 break ;
 case 1:
 [self.navigationController pushViewController:kalenderViewCon animated:YES];
 break;
 case 2:
 [self.navigationController pushViewController:wunschViewCon animated: YES];
 break;
 }
}

I have a problem making me The navigation controller is operating normally! If I click a cell of the table in RootViewController, it doesn’t seem to be the next ViewController.

The error message reads

“Application tried to push a nil view controller on target
.”

So I assigned something wrong, my guess, I might have missed the book I followed Important content.

So the problem appeared in my RootViewController.m:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:( NSIndexPath *)indexPath{

 UINavigationController *navigationController= [[UINavigationController alloc]init];

 switch ([indexPath row]) {

 case 0:
 [navigationController pushViewController:kundeViewCon animated:YES];
 break;

 case 1:
 [navigationController pushViewController:kalenderViewCon animated:YES];
 break;

 case 2:
 [navigationController pushViewController:wunschViewCon animated:YES];
 break;
} 
}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
 self.window = [ [UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
 // Override point for customization after application launch.

// Navigation Controller

 RootViewController *rootViewController = [[RootViewController alloc]init];

 navigationController = [[UINavigationController alloc]initWithRootViewController:rootViewController];

 self.window.backgroundColor = [UIColor whiteColor]; 

 [self.window addSubview:navigationController.view];
 [self.window makeKeyAndVisible];
 return YES;
}

So When I click on Cell, I get all the other ViewControllers I want to push. I just can’t see my fault or what I missed! ?

Maybe someone can help me and give me a hint! That’s great!

RootViewController already has its navigation controller-you created it in the app delegate. It doesn’t make sense to create a new navigation controller when selecting a cell. It should look more like this:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
 switch ([indexPath row]) {
 case 0:
 [self.navigationController pushViewController:kundeViewCon animated:YES];
 break;
 case 1:
 [self.navigationController pushViewController:kalenderViewCon animated:YES];
 break;
 case 2:
 [self.navigationController pushViewController:wunschViewCon animated:YES];
 break;
 }
}

Also, just make sure that when calling -pushViewController:animated: the view controllers (ie kundleViewCon, kalenderViewCon & wunschViewCon) are non-zero. They look like instance variables or properties – Just make sure to assign/start them early in the code, for example in -viewDidLoad.