CODEWITHSUNDEEP
xamarinprism
Cristiano Winter
Cristiano Winter

Reputation: 21

Prevent back navigation on prism navigation?

I'm trying to prevent the user from back navigation on prism xamarin forms.

I'm having difficulty because, when I get the event, the app changes the page.

How do I block back navigation on prism navigation?

Upvotes: 1

Views: 1894

Answers (2)

CVStrydom
CVStrydom

Reputation: 301

You can implement the IConfirmNavigationAsync or IConfirmNavigation interface in your ViewModel which gives you a method that returns a bool to allow or block navigation. You can then use the GetNavigationMode to determine if it is a backwards navigation:

Non-async method:

public class MyViewModel : BindableBase, IConfirmNavigation
{
    public bool CanNavigate(INavigationParameters parameters)
    {
        /* Prevent backward navigation */
        if (parameters.GetNavigationMode() == NavigationMode.Back) return false;

        return true;
    }
}

Async method (Great for showing confirmation popup before navigating back for example):

public class MyViewModel : BindableBase, IConfirmNavigationAsync
{
    public async Task<bool> CanNavigateAsync(INavigationParameters parameters)
    {
        /* Confirm unsaved changes */
        if (parameters.GetNavigationMode() == NavigationMode.Back) 
        {
            var confirmed = await alertService.DisplayAlertAsync("Unsaved Changes", "You have unsaved changes do you wish to continue?");
            return confirmed;
        }

        return true;
    }
}

Upvotes: 1

TeoVr81
TeoVr81

Reputation: 1009

You can try to intercept the back event. One way is to implement the interface INavigationAware in your ViewModel:

public void OnNavigatedTo(NavigationParameters parameters)
{
   if(parameters.GetNavigationMode()== NavigationMode.Back){
      //Here your code
   }
}

Or take a look to this discussion:

https://forums.xamarin.com/discussion/18565/override-cancel-pop-when-hardware-back-button-pressed-using-navigatepage

Upvotes: -1

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