Question

I have my app like this : a navigationBar in the app delegate with have a Controller1(UIViewController) like a rootController, in the controller1 i push controller2 ( UIViewController), the controller2 have 3 UINavigationController, and a Custom tabBar, each navigationController have a root controller, and finally i put all the navigationController in the CustomTabBar.

My question is : is this clean( good) to do like this ? If no how i can organize my project ?

MyAppDelegate.h 
@property (strong, nonatomic) UIWindow *window;
@property (strong, nonatomic) UINavigationController *navigationController;
@property (strong, nonatomic) CustomTabBar *tabBarController;

MyAppDelegate.m {
UIViewController *controller1 = [[UIViewController alloc] initWithNibName:nil bundle:nil];
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    // Override point for customization after application launch.
    self.window.backgroundColor = [UIColor whiteColor];
    navigationController = [[UINavigationController alloc] initWithRootViewController:controller1];
 self.window.rootViewController = navigationController;
}

controller1.h
    UIViewController controller2;
    UINavigationController *navigationController2;

    UIViewController controller3;
    UINavigationController *navigationController3;


    UIViewController controller3;
    UINavigationController *navigationController3;

controller1.m 
-(void)viewDidLoad{

viewController1 = [[UIViewController......
navigationController1 = [[UINavigationController alloc] initWithRootViewController:controller1];
....

AppDelegate *apDelegate= [UIApplication sharedApplication].delegate;

    apDelegate.tabBarController = [[CustomTabBar alloc] initWithNibName:nil bundle:nil];
   [apDelegate.tabBarController setViewControllers: [NSArray arrayWithObjects:navigationController1,navigationController2,navigationController3,nil]];
}

Answer 1

This is an excerpt from the apple documentation:

When deploying a tab bar interface, you must install this view as the root of your window. Unlike other view controllers, a tab bar interface should never be installed as a child of another view controller.

From my point of view it’s a bit tricky from the start to sort out how to use UITabBarController class, so in this case the better approach is to see some good manual. For me this one helps always when I start to mess around with this UI thing 🙂

Good luck.

EDIT:
In order to have your tabbar appear only in some concrete views, you have to hide your tabbar from the start of the app, and make it appear only when you really need it.
In order to hide it, you can use the method:

[theTabBar setHidden:YES];