显示模态后无法更改选项卡式页面的选项卡

Question

我在iOS中遇到“选项卡式页面”的问题。我在选项卡式页面中添加了5个导航页面。显示并关闭模态后，我无法在水龙头上更改选项卡。如果我按住另一个标签3-4秒（长按），则该标签被选中。不知道是什么问题。没有日志以及

相同的代码在Android上运行正常。请让我知道是否有人遇到过类似的问题。

主页代码

        private bool tabsConfigured = false;

        public HomeView (HomeViewModel viewModel)
        {
            InitializeComponent();
            NavigationPage.SetHasNavigationBar(this, false);

            if (Device.RuntimePlatform == Device.Android)
            {
                On<Xamarin.Forms.PlatformConfiguration.Android>().SetToolbarPlacement(ToolbarPlacement.Bottom);
                On<Xamarin.Forms.PlatformConfiguration.Android>().SetBarItemColor(Color.FromHex("#c1c1c1"));
                On<Xamarin.Forms.PlatformConfiguration.Android>().SetBarSelectedItemColor(Color.White);
                On<Xamarin.Forms.PlatformConfiguration.Android>().SetIsSwipePagingEnabled(false);
                On<Xamarin.Forms.PlatformConfiguration.Android>().SetOffscreenPageLimit(5);
            }
            else if (Device.RuntimePlatform == Device.iOS)
            {
                this.BarBackgroundColor = Color.FromHex("#0c293d");
                //this.BarTextColor = Color.White;
            }

            this.ViewModel = viewModel;
            this.ViewModel.SwitchTabAction = OnSwitchTabFromViewModel;

#if __IOS__
            InitTabs();
#endif
        }

        protected override void OnAppearing()
        {
            base.OnAppearing();
#if __ANDROID__
            InitTabs();
#endif
        }

        protected override void OnDisappearing()
        {
            base.OnDisappearing();
            this.ViewModel.SwitchTabAction = null;
        }

        private void InitTabs()
        {
            var logService = AutofacUtil.Instance.Resolve<ILogService>();

            try
            {
                 if (tabsConfigured) return;

                this.Children.Add(this.GetInitialTabPage<DestinationsViewModel>("tab_guide", "Guide"));
                this.Children.Add(this.GetInitialTabPage<GroupsViewModel>("tab_chats", "Groups"));
                this.Children.Add(this.GetInitialTabPage<ItineraryViewModel>("tab_itineraries", "Itineraries"));
                this.Children.Add(this.GetInitialTabPage<ExpenseViewModel>("tab_expenses", "Expenses"));
                this.Children.Add(this.GetInitialTabPage<MoreViewModel>("tab_mores", "More"));
#if __ANDROID__
                this.BatchCommit();
#endif

                tabsConfigured = true; //Important to be here.

                //Setting Current Page
                if (this.ViewModel.ActiveTab >= 1)
                    this.CurrentPage = this.Children[this.ViewModel.ActiveTab];
                else if (this.ViewModel.ActiveTab == 0) //OnPageChanged doesn't get called for first tab.
                {
                    CurrentPage = this.Children[this.ViewModel.ActiveTab];
                    OnPageChanged();
                }
            }
            catch (Exception ex)
            {
                logService.Error(ex);
            }
        }

        public NavigationPage GetInitialTabPage<T>(string icon, string title) where T : BaseCoreViewModel
        {
            Page page = new TabLoadingPage(typeof(T));

            NavigationPage navigationPage = new NavigationPage(page);
            navigationPage.Icon = icon;
            navigationPage.Title = title;
            navigationPage.BarBackgroundColor = Color.FromHex("#0c293d");
            navigationPage.BarTextColor = Color.White;
            return navigationPage;
        }

显示模态的代码。调用PushModalAsync以显示模式。

    public class NavigationService : INavigationService
    {
        private INavigation _mainNavigation = null;
        private INavigation _currentTabNavigation = null;
        private INavigation _currentModalNavigation = null;
        private NavigationPage _currentModalNavPage = null;

        public void SetMainXamarinFormsNavigation(INavigation navigation)
        {
            _mainNavigation = navigation;
        }

        public void SetTabXamarinFormsNavigation(INavigation navigation)
        {
            _currentTabNavigation = navigation;
        }

        public async Task PushAsync<T>(object parameters = null, bool animate = true) where T : BaseCoreViewModel
        {
            var page = ViewCreator.CreateViewAndViewModelAndCallInit<T>(parameters);

            INavigation currentNavigation = null;
            if (_currentModalNavigation != null)
                currentNavigation = _currentModalNavigation;
            else if (_currentTabNavigation != null)
                currentNavigation = _currentTabNavigation;
            else if (_mainNavigation != null)
                currentNavigation = _mainNavigation;

#if __IOS__
            var currentPage = currentNavigation.NavigationStack.ElementAt(currentNavigation.NavigationStack.Count - 1);
            var oldTitle = currentPage.Title;
            currentPage.Title = "Back";
#endif
            await currentNavigation.PushAsync(page, animate);

#if __IOS__
            currentPage.Title = oldTitle;
#endif
        }

        public async Task PushModalAsync<T>(object parameters = null, bool animate = true) where T : BaseCoreViewModel
        {
            if (_mainNavigation == null) return;

#if __ANDROID__
            var emptyPage = new FirstEmptyNavPage();
#endif
            var startPage = ViewCreator.CreateViewAndViewModelAndCallInit<T>(parameters, true);

#if __ANDROID__
            _currentModalNavPage = new NavigationPage(emptyPage);
#else
            _currentModalNavPage = new NavigationPage(startPage);
#endif

            _currentModalNavPage.Popped += _currentModalNavPage_Popped;
            _currentModalNavPage.BarBackgroundColor = Color.FromHex("#0c293d");
            _currentModalNavPage.BarTextColor = Color.White;

#if __ANDROID__
            await _currentModalNavPage.PushAsync(startPage);
#endif

            await _mainNavigation.PushModalAsync(_currentModalNavPage, animate);

            if (_currentModalNavPage != null)
                _currentModalNavigation = _currentModalNavPage.Navigation;
        }

        private async void _currentModalNavPage_Popped(object sender, NavigationEventArgs e)
        {
            if (_currentModalNavPage != null && _currentModalNavPage.CurrentPage is FirstEmptyNavPage)
            {
                _currentModalNavPage.Popped -= _currentModalNavPage_Popped;
                _currentModalNavPage = null;
                _currentModalNavigation = null;
                await _mainNavigation.PopModalAsync(false);
            }
        }

        public async Task PopAsync(bool animate = true)
        {
            if (_currentModalNavigation != null && _currentModalNavigation.NavigationStack.Count > 1)
                await _currentModalNavigation.PopAsync(animate);
            else if (_currentModalNavigation != null && _currentModalNavigation.NavigationStack.Count > 1)
            {
                await _currentModalNavigation.PopModalAsync(animate);
                _currentModalNavigation = null;
            }
            else if (_currentTabNavigation != null)
                await _currentTabNavigation.PopAsync(animate);
            else if (_mainNavigation != null)
                await _mainNavigation.PopAsync(animate);
        }

        public async Task PopModalAsync(bool animate = true)
        {
            if (_currentModalNavigation != null)
            {
                await _currentModalNavigation.PopModalAsync(animate);
                _currentModalNavigation = null;
            }
        }
    }