public App( ViewModelFactory viewModelFactory, PageFactory pageFactory, Func <Page, NavigationPage> navigationPageFactory, BackgroundService backgroundService, IThemeService themeService) { InitializeComponent(); _backgroundService = backgroundService; RequestedThemeChanged += (s, e) => { themeService.CurrentTheme = e.RequestedTheme switch { OSAppTheme.Dark => ThemeType.Dark, OSAppTheme.Light => ThemeType.Light, _ => ThemeType.System }; themeService.ApplyCurrentTheme(); }; themeService.ApplyCurrentTheme(); var vm = viewModelFactory(typeof(CreationListPageViewModel), null); var page = pageFactory(typeof(CreationListPage), vm); var navigationPage = navigationPageFactory(page); navigationPage.BarBackgroundColor = Color.Red; navigationPage.BarTextColor = Color.White; MainPage = navigationPage; }