Disable NSToolbar Tabs

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

@@ -59,6 +59,7 @@ void IAppearanceObserver.OnAppearanceChanged(ShellAppearance appearance)
 
 		public ShellItemRenderer(IShellContext context)
 		{
+			this.DisableiOS18ToolbarTabs();
 			_context = context;
 		}
 
@@ -438,7 +439,19 @@ void UpdateTabBarHidden()
 			if (ShellItemController == null)
 				return;
 
+
+#if IOS18_0_OR_GREATER || MACCATALYST18_0_OR_GREATER
+			if (OperatingSystemMacCatalyst18Workaround.IsMacCatalystVersionAtLeast18() || OperatingSystem.IsIOSVersionAtLeast(18))
+			{
+				TabBarHidden = !ShellItemController.ShowTabs;
+			}
+			else
+			{
+				TabBar.Hidden = !ShellItemController.ShowTabs;
+			}
+#else
 			TabBar.Hidden = !ShellItemController.ShowTabs;
+#endif
 		}
 	}
 }

src/Controls/src/Core/Compatibility/Handlers/TabbedPage/iOS/TabbedRenderer.cs

@@ -39,6 +39,7 @@ public class TabbedRenderer : UITabBarController, IPlatformViewHandler
 		[Microsoft.Maui.Controls.Internals.Preserve(Conditional = true)]
 		public TabbedRenderer()
 		{
+			this.DisableiOS18ToolbarTabs();
 			_viewHandlerWrapper = new ViewHandlerDelegator<TabbedPage>(Mapper, CommandMapper, this);
 		}
 

src/Core/src/OperatingSystemMacCatalyst18Workaround.cs

@@ -0,0 +1,22 @@
+using System;
+
+namespace Microsoft.Maui.Platform
+{
+    #if PLATFORM
+	internal static partial class OperatingSystemMacCatalyst18Workaround
+	{
+        public static bool IsMacCatalystVersionAtLeast18()
+        {
+            #if !MACCATALYST
+            return false;
+            #else
+            // Delete all uses of this once this is merged
+            // /https://github.com/xamarin/xamarin-macios/issues/21390
+
+
+            return Environment.OSVersion.Version.Major >= 18;
+            #endif
+        }
+    }
+    #endif
+}

src/Core/src/Platform/iOS/TabbedViewExtensions.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Text;
 using Foundation;
 using Microsoft.Maui.Graphics;
@@ -9,6 +10,22 @@ namespace Microsoft.Maui.Platform
 {
 	internal static class TabbedViewExtensions
 	{
+		internal static void DisableiOS18ToolbarTabs(this UITabBarController tabBarController)
+		{
+			#if IOS18_0_OR_GREATER || MACCATALYST18_0_OR_GREATER
+			// Should apply to iOS and Catalyst
+			if (OperatingSystemMacCatalyst18Workaround.IsMacCatalystVersionAtLeast18()) //https://github.com/xamarin/xamarin-macios/issues/21390		
+			{
+				tabBarController.TraitOverrides.HorizontalSizeClass = UIUserInterfaceSizeClass.Compact;
+				tabBarController.Mode = UITabBarControllerMode.TabSidebar;
+			}
+			else if (OperatingSystem.IsIOSVersionAtLeast(18, 0) && UIDevice.CurrentDevice.UserInterfaceIdiom == UIUserInterfaceIdiom.Pad)
+			{
+				tabBarController.TraitOverrides.HorizontalSizeClass = UIUserInterfaceSizeClass.Compact;
+			}
+			#endif
+		}
+
 		[System.Runtime.Versioning.SupportedOSPlatform("ios15.0")]
 		[System.Runtime.Versioning.SupportedOSPlatform("tvos15.0")]
 		internal static void UpdateiOS15TabBarAppearance(
@@ -104,4 +121,4 @@ internal static void UpdateiOS15TabBarAppearance(
 			tabBar.StandardAppearance = tabBar.ScrollEdgeAppearance = _tabBarAppearance;
 		}
 	}
-}
+}