Consider the following situation:

• MVVM Pattern
• AutosuggestBox in the title bar
• Doing something like searching through a box in all views

implement ITitleBarAutoSuggestBoxAware in your viewmodels:

public partial class GalleryViewModel : ITitleBarAutoSuggestBoxAware
{
    public void OnAutoSuggestBoxTextChanged(AutoSuggestBox sender, AutoSuggestBoxTextChangedEventArgs args)
    {
        Search(sender.Text);
    }

    public void OnAutoSuggestBoxQuerySubmitted(AutoSuggestBox sender, AutoSuggestBoxQuerySubmittedEventArgs args)
    {
        Search(sender.Text);
    }
}

and in your MainPage or wherever your box is located:

private void OnTextChanged(AutoSuggestBox sender, AutoSuggestBoxTextChangedEventArgs args)
{
    AutoSuggestBoxHelper.OnITitleBarAutoSuggestBoxTextChangedEvent(sender, args, NavFrame);
}

private void OnQuerySubmitted(AutoSuggestBox sender, AutoSuggestBoxQuerySubmittedEventArgs args)
{
    AutoSuggestBoxHelper.OnITitleBarAutoSuggestBoxQuerySubmittedEvent(sender, args, NavFrame);
}

then you should set DataContext to your ViewModel:

public GalleryPage()
{
    ViewModel = App.GetService<GalleryViewModel>();
    this.InitializeComponent();
    DataContext = ViewModel;
}

public ArchivePage()
{
    ViewModel = App.GetService<ArchiveViewModel>();
    this.InitializeComponent();
    DataContext = ViewModel;
}