26598 - Fix for Tabbar disappears when navigating back from page with hidden TabBar in iOS 18

src/Controls/src/Core/Compatibility/Handlers/Shell/iOS/ShellPageRendererTracker.cs

@@ -139,10 +139,12 @@ protected virtual void UpdateTabBarVisible()
 				return;
 			}
 
-			var tabBarVisible =
-				(Page.FindParentOfType<ShellItem>() as IShellItemController)?.ShowTabs ?? Shell.GetTabBarIsVisible(Page);
-
-			ViewController.HidesBottomBarWhenPushed = !tabBarVisible;
+			var tabBarVisible = (Page.FindParentOfType<ShellItem>() as IShellItemController)?.ShowTabs ?? Shell.GetTabBarIsVisible(Page);
+			// In iOS 18, the tab bar visibility is effectively managed by the TabBarHidden property in ShellItemRenderer.
+			if (!(OperatingSystemMacCatalyst18Workaround.IsMacCatalystVersionAtLeast18() || OperatingSystem.IsIOSVersionAtLeast(18)))
+			{
+				ViewController.HidesBottomBarWhenPushed = !tabBarVisible;
+			}
 		}
 
 		void OnToolbarPropertyChanged(object sender, PropertyChangedEventArgs e)

src/Controls/src/Core/Shell/ShellSection.cs

@@ -410,16 +410,27 @@ async Task PrepareCurrentStackForBeingReplaced(ShellNavigationRequest request, S
 								continue;
 						}
 
-						// This is the page that we will eventually get to once we've finished
-						// modifying the existing navigation stack
-						// So we want to fire appearing on it						
-						navPage.SendAppearing();
-
+						// We use this inside ModalNavigationManager to indicate that we're going to be popping multiple
+						// modal pages so we don't want it to fire any appearing events
 						IsPoppingModalStack = true;
 
 						while (navStack.Count > popCount && Navigation.ModalStack.Count > 0)
 						{
 							bool isAnimated = animate ?? IsNavigationAnimated(navStack[navStack.Count - 1]);
+
+							var nextModalPageToPopIndex = navStack.Count - 2;
+							// Check if we've reached the last modal page to pop before revealing the target modal page.
+							// The IsPoppingModalStack flag instructs ModalNavigationManager to suppress lifecycle events
+							// during a bulk pop operation.
+							// This approach is required because the standard modal APIs do not support popping multiple
+							// pages at once, while Shell URI navigation does.
+							// Ideally, this logic would be refactored into ModalNavigationManager to expose batch popping
+							// via the INavigation APIs.
+							if (nextModalPageToPopIndex >= 0 && navStack[nextModalPageToPopIndex] == navPage)
+							{
+								IsPoppingModalStack = false;
+							}
+
 							if (Navigation.ModalStack.Contains(navStack[navStack.Count - 1]))
 							{
 								await PopModalAsync(isAnimated);

src/Controls/tests/Core.UnitTests/ShellModalTests.cs

@@ -157,6 +157,18 @@ public async Task PoppingModalStackFiresAppearingOnRevealedModalPage()
 			Assert.True(true);
 		}
 
+		[Fact]
+		public async Task PoppingModalStackFiresAppearingOnRevealedNonModalPage()
+		{
+			Shell shell = new TestShell();
+			shell.Items.Add(CreateShellItem(shellContentRoute: "MainContent"));
+
+			await shell.GoToAsync($"LifeCyclePage/ContentPage/ModalTestPage2/ModalTestPage");
+			var lifeCyclePage = shell.Descendants().OfType<ShellLifeCycleTests.LifeCyclePage>().First();
+			Assert.False(lifeCyclePage.Appearing);
+			await shell.GoToAsync($"../../..");
+			Assert.True(lifeCyclePage.Appearing);
+		}
 
 		[Fact]
 		public async Task ModalPopsWhenSwitchingShellContent()

src/Controls/tests/TestCases.HostApp/Issues/Issue26598.cs

@@ -0,0 +1,135 @@
+using Microsoft.Maui.Controls;
+
+namespace Maui.Controls.Sample.Issues;
+[Issue(IssueTracker.Github, 26598, "Tabbar disappears when navigating back from page with hidden TabBar in iOS", PlatformAffected.iOS)]
+public class Issue26598 : TestShell
+{
+	TabBar tabBar = new TabBar();
+
+	// Create first ShellContent
+	ShellContent homeShellContent = new ShellContent
+	{
+		ContentTemplate = new DataTemplate(() => new Issue26598Home()),
+		Title = "HomeTab",
+		AutomationId = "Issue26598Home",
+		Route = nameof(Issue26598Home)
+	};
+
+	// Create second ShellContent
+	ShellContent recentShellContent = new ShellContent
+	{
+		ContentTemplate = new DataTemplate(() => new Issue26598Recent()),
+		Title = "RecentTab",
+		Route = nameof(Issue26598Recent)
+	};
+
+	protected override void Init()
+	{
+		Routing.RegisterRoute("Issue26598Inner", typeof(Issue26598Inner));
+		Routing.RegisterRoute(nameof(Issue26589NonTab), typeof(Issue26589NonTab));
+		tabBar.Items.Add(homeShellContent);
+		tabBar.Items.Add(recentShellContent);
+		Items.Add(tabBar);
+	}
+
+	public class Issue26598Home : ContentPage
+	{
+		VerticalStackLayout stackLayout;
+		Button button;
+		public Issue26598Home()
+		{
+			Title = "Home";
+			HeightRequest = 200;
+			stackLayout = new VerticalStackLayout();
+			button = new Button()
+			{
+				Text = "Navigate to InnerTab",
+				AutomationId = "NavigateToInnerTab",
+				VerticalOptions = LayoutOptions.Center,
+				HorizontalOptions = LayoutOptions.Center,
+			};
+			button.Clicked += Button_OnClicked;
+			stackLayout.Add(button);
+			Shell.SetTabBarIsVisible(this, false);
+			this.Content = stackLayout;
+		}
+
+		private void Button_OnClicked(object sender, EventArgs e)
+		{
+			Shell.Current.GoToAsync(nameof(Issue26598Inner));
+		}
+
+	}
+
+	public class Issue26598Inner : ContentPage
+	{
+		VerticalStackLayout stackLayout;
+		Button button;
+		public Issue26598Inner()
+		{
+			Title = "InnerTab";
+			stackLayout = new VerticalStackLayout();
+			button = new Button()
+			{
+				Text = "Navigate to TabBarPage",
+				AutomationId = "NavigateToTabBarPage",
+				VerticalOptions = LayoutOptions.Center,
+				HorizontalOptions = LayoutOptions.Center,
+			};
+			button.Clicked += Button_OnClicked;
+			stackLayout.Add(button);
+			Shell.SetTabBarIsVisible(this, true);
+			this.Content = stackLayout;
+		}
+
+		private void Button_OnClicked(object sender, EventArgs e)
+		{
+			Shell.Current.GoToAsync(nameof(Issue26589NonTab));
+		}
+
+	}
+
+	public class Issue26598Recent : ContentPage
+	{
+		VerticalStackLayout stackLayout;
+		Label label;
+		public Issue26598Recent()
+		{
+			Title = "Recent";
+			HeightRequest = 200;
+
+			stackLayout = new VerticalStackLayout();
+			label = new Label()
+			{
+				Text = "Page Loaded in Recent Tab",
+				VerticalOptions = LayoutOptions.Center,
+				HorizontalOptions = LayoutOptions.Center,
+
+			};
+			stackLayout.Add(label);
+			Shell.SetTabBarIsVisible(this, true);
+			this.Content = stackLayout;
+		}
+	}
+	public class Issue26589NonTab : ContentPage
+	{
+		VerticalStackLayout stackLayout;
+		Label label1;
+		public Issue26589NonTab()
+		{
+			Title = "NoTabBarPage";
+			stackLayout = new VerticalStackLayout();
+			label1 = new Label()
+			{
+				Text = "This is Non TabBarPage",
+				AutomationId = "Issue26589NonTab",
+				VerticalOptions = LayoutOptions.Center,
+				HorizontalOptions = LayoutOptions.Center,
+			};
+			stackLayout.Add(label1);
+			Shell.SetTabBarIsVisible(this, false);
+			this.Content = stackLayout;
+		}
+
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue26598.cs

@@ -0,0 +1,47 @@
+using NUnit.Framework;
+using NUnit.Framework.Legacy;
+using UITest.Appium;
+using UITest.Core;
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue26598 : _IssuesUITest
+{
+	public override string Issue => "Tabbar disappears when navigating back from page with hidden TabBar in iOS";
+
+#if ANDROID
+    const string back = "";
+#else
+	const string back = "InnerTab";
+#endif
+
+	public Issue26598(TestDevice device) : base(device)
+	{
+	}
+
+	[Test]
+	[Category(UITestCategories.Shell)]
+	public void TabBarShouldbeVisibleNavigatingBackFromNonTabbedPage()
+	{
+		// Is a iOS issue; see https://github.com/dotnet/maui/issues/26598
+		// Initially TabBar for Issue26598Home is hidden 
+		App.WaitForElement("NavigateToInnerTab");
+		App.Click("NavigateToInnerTab");
+
+		// Case 1 - After navigating to Inner Page ,  the TabBar should be visible
+		App.WaitForElement("RecentTab");
+
+		// Case 2 - Navigate to the InnerTabPage where the TabBar is hidden
+		App.WaitForElement("NavigateToTabBarPage");
+		App.Click("NavigateToTabBarPage");
+		App.WaitForElement("Issue26589NonTab");
+
+		// Case 3 - Navigate back to the HomeTab, the TabBar should be visible
+		App.TapBackArrow(back);
+		App.WaitForElement("RecentTab");
+		App.Click("RecentTab");
+		App.WaitForElement("HomeTab");
+		App.Click("HomeTab");
+		App.WaitForElement("RecentTab");
+	}
+}
+