IOS UINavigationController, pushViewController not working

Question

Good evening,

I currently have two UIViewControllers. My appDelegate looks like this

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    struct CGRect rect = [[UIScreen mainScreen] bounds];
    rect.origin.x = rect.origin.y = 0.0f;

    _viewController = [[sandboxViewController alloc] init];

    UINavigationController *nc = [[UINavigationController alloc] initWithRootViewController:_viewController];

    _window = [[UIWindow alloc] initWithFrame:rect];

    [_window makeKeyAndVisible];
    [_window addSubview:nc.view];

    return YES;
}

The viewController looks like this:

    - (void)loadView {
        self.view = [[UIView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 320.0f, 480.0f)];
        self.view.backgroundColor = [UIColor whiteColor];
        self.navigationItem.title = @"Master View";
    }

    - (void)viewDidLoad
    {
        [super viewDidLoad];
        UIButton *infoButton = [UIButton buttonWithType:UIButtonTypeInfoLight];
        [infoButton addTarget:self action:@selector(switchView:) forControlEvents:UIControlEventTouchUpInside];
        self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:infoButton];
    }

    - (void)switchView:(id)obj {
        if(![self navigationController])
            NSLog(@"navigationController IS NIL!!!");
        if(!_secondView) 
            _secondView = [[secondViewController alloc] init];
        [self.navigationController pushViewController:_secondView animated:YES];
}

By clicking on the info button, that was added to the right side on the navigation bar, I want to switch to the secondView. This, however, is not happening because navigationController logs as nil ! What am I missing here?

Any help is truly appreciated!

Mudriy Ilya · Accepted Answer · 2016-03-01 11:35:52Z

1

You don't have to create the window, it should already exist.

//_window = [[UIWindow alloc] initWithFrame:rect]; //remove this line    
[self.window makeKeyAndVisible]; //use the ivar
[self.window addSubview:nc.view];

edited Mar 1, 2016 at 11:35

Mudriy Ilya

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answered Dec 15, 2011 at 5:58

railwayparade

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4 Comments

Pascal Over a year ago

Thank you for the hint! I changed the code but it's not working! It says expected rootViewCintoller at the end of application launch

railwayparade Over a year ago

ah you need to set rootViewController on the window

railwayparade Over a year ago

self.window.rootViewController = nc;

Pascal Over a year ago

Railway, thx!! That did the trick! However I had to add self.window alloc/initWithFrame to make it to work! What exactly is the difference between using self.window and _window?

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