The NavigationService is in charge of handling the navigation between app pages.
NavigationService is a class consumed using IoC that uses the NavigateTo method to navigate between pages. It uses the page key as a parameter. These page keys are registered in the PageService constructor and correspond to the Page's ViewModel FullName.
All ViewModels can implement the INavigationAware interface to execute code on navigation events.
public class MainViewModel : ObservableRecipient, INavigationAware
{
public void OnNavigatedTo(object parameter)
{
// Run code when the app navigates to this page
}
public void OnNavigatedFrom()
{
// Run code when the app navigates away from this page
}
}The ActivateAsync method in the ActivationService class tries to get a ShellPage from the IoC and set the content of the applications MainWindow (App.MainWindow) to the ShellPage. If the ShellPage is not registered in the ConfigureServices method from the App.xaml.cs file, the content of the MainWindow will be set to a new Frame.
Classes that extend from ActivationHandler can perform the first navigation in the App, if it doesn't happen, the DefaultActivationHandler navigates to the home page.
This project type adds a ShellPage that sets the NavigationService's frame to a frame within the NavigationView on the ShellPage. The NavigationService will do future navigation in this frame.
<Page>
<NavigationView>
<Grid>
<Frame x:Name="shellFrame" />
</Grid>
</NavigationView>
</Page>