Difficulty with TabBarControllers intermixed with NavigationControllers - ios

Question

I have a Xamarin.iOS app where I have the following structure:
NavController (root: Login)
--> TabBarController (Home) - (Search) - (Profile)
------> NavController (root: Home)
------------->TableController
----------------->DetailController
------>NavController (root: Search)
...etc
I am currently having difficulties working with the navigation items, specifically the back button item.
I never want to go back to the login page via the back button, so in my HomeController, I hide the back button by saying
TabBarController.NavigationItem.HidesBackButton = true;
When I go to the next screen (TableController) I want to see the back button that goes back to the HomeController, however my current approach has a back button to the Login Controller
this.TabBarController.NavigationItem.HidesBackButton = false;
Thanks for any help

Answer 1

For the effect you want, I suggest you create an object(I use "RootController" as an example) to manage the app's Window.RootController.
I don't know if you have some experience for change window's RootController, so just follow my step:
At first create a new project, remove the storyboard and Viewcontroller.cs.(Don't forget remove the bundle for storyboard in the info.plist)
Then rewrite your AppDelegate.cs, like this:
[Register ("AppDelegate")]
public class AppDelegate : UIApplicationDelegate
{
UIWindow window;
public override bool FinishedLaunching (UIApplication application, NSDictionary launchOptions)
{
// create a new window instance based on the screen size
window = new UIWindow (UIScreen.MainScreen.Bounds);
window.RootViewController = RootController.Instance.LoginController;
window.MakeKeyAndVisible ();
return true;
}
public override void OnResignActivation (UIApplication application)
{
// Invoked when the application is about to move from active to inactive state.
// This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message)
// or when the user quits the application and it begins the transition to the background state.
// Games should use this method to pause the game.
}
public override void DidEnterBackground (UIApplication application)
{
// Use this method to release shared resources, save user data, invalidate timers and store the application state.
// If your application supports background exection this method is called instead of WillTerminate when the user quits.
}
public override void WillEnterForeground (UIApplication application)
{
// Called as part of the transiton from background to active state.
// Here you can undo many of the changes made on entering the background.
}
public override void OnActivated (UIApplication application)
{
// Restart any tasks that were paused (or not yet started) while the application was inactive.
// If the application was previously in the background, optionally refresh the user interface.
}
public override void WillTerminate (UIApplication application)
{
// Called when the application is about to terminate. Save data, if needed. See also DidEnterBackground.
}
}
And this is RootController.cs which include a UINavigationController and a UITabBarController(Home - Search - Profile):
public class RootController
{
private static RootController instance;
public static RootController Instance {
get {
if (instance == null)
instance = new RootController ();
return instance;
}
}
private static UINavigationController loginController;
public UINavigationController LoginController {
get {
if (loginController == null)
InitLoginController ();
return loginController;
}
}
private void InitLoginController()
{
UIViewController loginViewController = new UIViewController (){ Title = "LoginController" };
loginViewController.View.Frame = UIScreen.MainScreen.Bounds;
loginViewController.View.BackgroundColor = UIColor.Red;
loginViewController.NavigationItem.SetRightBarButtonItem (new UIBarButtonItem ("MainTab",UIBarButtonItemStyle.Done, delegate {
UIApplication.SharedApplication.KeyWindow.RootViewController = RootController.Instance.MainTabController;
}),true);
loginController = new UINavigationController (loginViewController);
}
private static UITabBarController mainTabController;
public UITabBarController MainTabController {
get {
if (mainTabController == null)
InitMainTabController ();
return mainTabController;
}
set {
mainTabController = value;
}
}
private void InitMainTabController ()
{
mainTabController = new UITabBarController ();
mainTabController.ViewControllers = new UIViewController [] {
new UINavigationController(new HomeViewController() {
TabBarItem = new UITabBarItem (UITabBarSystemItem.Favorites,0)
}),
new UINavigationController (new UIViewController ()
{
Title = "SearchController",
TabBarItem = new UITabBarItem (UITabBarSystemItem.Search,1)
}),
new UINavigationController (new UIViewController ()
{
Title = "ProfileController",
TabBarItem = new UITabBarItem (UITabBarSystemItem.More,2)
})
};
mainTabController.SelectedIndex = 0;
}
}
And this is HomeController.cs which can push an UITableViewController as you wish and also has a button to return to LoginController if you needed:
public class HomeViewController : UIViewController
{
public HomeViewController ()
{
Title = "HomeController";
this.View.Frame = UIScreen.MainScreen.Bounds;
this.View.BackgroundColor = UIColor.Green;
//Set a button to return to loginController
this.NavigationItem.SetLeftBarButtonItem (new UIBarButtonItem ("LoginC",UIBarButtonItemStyle.Done, delegate {
UIApplication.SharedApplication.KeyWindow.RootViewController = RootController.Instance.LoginController;
}),true);
//Set a button to go to tableController
UITableViewController tableViewController = new UITableViewController (){ Title = "TableViewController" };
tableViewController.View.Frame = UIScreen.MainScreen.Bounds;
tableViewController.View.BackgroundColor = UIColor.White;
tableViewController.HidesBottomBarWhenPushed = true;//To make tabbar disappear
this.NavigationItem.SetRightBarButtonItem (new UIBarButtonItem ("TableView",UIBarButtonItemStyle.Done, delegate {
this.NavigationController.PushViewController(tableViewController,true);
}),true);
}
}
You can add your own ViewController in RootController.cs instead of my sample controllers.
If you still have some problems, just leave it here, I'll check it latter.
Hope it can help you.