MainPage.xaml.cs

protected override async void OnNavigatedTo(NavigationEventArgs e)
{
    base.OnNavigatedTo(e);

    if (!string.IsNullOrEmpty(e.Parameter as string))
    {
        // Check if all paramters for accessing the light are set
        if (App.HomeMatic != null && App.SelectedLightId != 0)
        {
            var args = ((string)e.Parameter).Split('|');
            if (args[1] == "on")
                // Switch light on
            else
                // Switch light off
        }                
    }
}