What is the best solution for "reseting" the Authentication stack? - xamarin

Question

Currently in my application I have two Navigation stacks.
Authentication
Main
My Authentication stack looks like this:
Splash Page
Choose Create or Login Page
Login Page
After that I call:
CoreMethods.SwitchOutRootNavigation(NavigationContext.Main);
This all works fine.
When I call Logout from within the Main stack like this:
CoreMethods.SwitchOutRootNavigation(NavigationContext.Authentication);
I will currently be on "Login Page", but I really want it to be the first page "Splash Page".
Having the Navigation stacks remember the stack history is perfect for all other cases.
Question: What is the best solution for "reseting" the Authentication stack?

Answer 1

What I normally do in my apps is following.
I have IAuthenticationService which has a State property, which can be LoggedIn or LoggedOut. When session state changed due to explicit login, or for instance token expires, I set the State to LoggedOut. Also I fire a broadcast message SessionStateChanged through Messenger, so I can catch this message all around the app, and react correspondingly in UI level, like change screen states and so on.
If need to completely log the user, I mean show login page when State is LoggedOut, which is your case, I do the following. I use Xamarin.Forms, but the approach would be similar if you use native iOS or Android.
In my main App class (the one which derives from Xamarin.Forms.Application) I create a method call UpdateMainPage, something like this
private async void UpdateMainPage()
{
if (_authService.State == SessionState.LoggedIn)
MainPage = new NavigationPage(new RequestPage());
else
MainPage = new NavigationPage(new SignInPage());
}
What happens I just change the root page of the application to SignIn flow or Main flow depending on SessionState. Then in my constructor I do the following.
public FormsApp()
{
InitializeComponent();
_authService = Mvx.Resolve<IAuthenticationService>();
UpdateMainPage();
var messenger = Mvx.Resolve<IMvxMessenger>();
_sessionStateChangedToken = messenger.Subscribe<SessionStateChangedMessage>(HandleSessionStateChanged);
}
What I need to do, I need to setup main page beforehand, then I subscribe to SessionStateChanged event, where I trigger UpdateMainPage
private void HandleSessionStateChanged(SessionStateChangedMessage sessionStateChangedMessage)
{
UpdateMainPage();
}
I used this approach for several apps, and it work perfect for me. Hope this helps

Answer 2

I had the very same problem recently and this is what I did:
Navigation stacks:
public enum NavigationStacks {Authentication, Main}
In the App.xaml.cs:
//Navigation stack when user is authenticated.
var mainPage = FreshPageModelResolver.ResolvePageModel<MainPageModel>();
var mainNavigation = new FreshNavigationContainer(MainPage, NavigationStacks.Main.ToString());
//Navigation stack for when user is not authenticated.
var splashScreenPage= FreshPageModelResolver.ResolvePageModel<SplashScreenPageModel>();
var authenticationNavigation = new FreshNavigationContainer(splashScreenPage, NavigationStacks.Authentication.ToString());
here you can leverage James Montemagno's Settings Plugin
if (Settings.IsUserLoggedIn)
{
MainPage = mainNavigation;
}
else
{
MainPage = authenticationNavigation;
}
So far you had already done the code above. But the idea for the problem is to clear the authentication stack except the root page i.e splash Screen:
public static void PopToStackRoot(NavigationStacks navigationStack)
{
switch (navigationStack)
{
case NavigationStacks.Authentication:
{
var mainPage = FreshPageModelResolver.ResolvePageModel<MainPageModel>();
var mainNavigation = new FreshNavigationContainer(MainPage, NavigationStacks.Main.ToString());
break;
}
case NavigationStacks.Main:
{
var splashScreenPage= FreshPageModelResolver.ResolvePageModel<SplashScreenPageModel>();
var authenticationNavigation = new FreshNavigationContainer(splashScreenPage, NavigationStacks.Authentication.ToString());
break;
}
}
}
And finally here is the code inside Logout command:
private void Logout()
{
Settings.IsUserLoggedIn = false;
NavigationService.PopToStackRoot(NavigationStacks.Authentication);
CoreMethods.SwitchOutRootNavigation(NavigationStacks.Authentication.ToString());
}
I know there may be better and more efficient approaches. But that worked for me.