[iOS] Fixed the App crashes when navigating to a page containing a map more than once (#29369)

* Committed the test case and sample

* committed the fix

* Modified the test sample

* Updated the Test condition for windows

* Removed unwanted spaces

* Optimized the fix

* Change the code into modern c#

Author: Ahamed-Ali

src/Controls/tests/TestCases.HostApp/Issues/Issue20612.cs

@@ -0,0 +1,94 @@
+using Microsoft.Maui.Maps;
+
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 20612, "Disconnecting Map Handler causes Map to crash on second page entrance and moving to region.", PlatformAffected.iOS | PlatformAffected.macOS)]
+public class Issue20612 : TestNavigationPage
+{
+    protected override void Init()
+    {
+        PushAsync(new Issue20612page1());
+    }
+}
+
+public class Issue20612page1 : ContentPage
+{
+    public Issue20612page1()
+    {
+        var openMapButton = new Button
+        {
+            Text = "Navigate to Map page",
+            HorizontalOptions = LayoutOptions.Center,
+            VerticalOptions = LayoutOptions.Center,
+            AutomationId = "MapButton"
+        };
+
+        openMapButton.Clicked += (s, e) =>
+        {
+            Navigation.PushAsync(new Issue20612page2());
+        };
+        Content = openMapButton;
+    }
+}
+
+public class Issue20612page2 : ContentPage
+{
+    private Microsoft.Maui.Controls.Maps.Map _map;
+
+    public Issue20612page2()
+    {
+        _map = new Microsoft.Maui.Controls.Maps.Map
+        {
+            HorizontalOptions = LayoutOptions.Fill,
+            VerticalOptions = LayoutOptions.Fill,
+            BackgroundColor = Colors.Red
+        };
+
+        var goBackButton = new Button
+        {
+            Text = "Go back",
+            HorizontalOptions = LayoutOptions.Center,
+            VerticalOptions = LayoutOptions.Center,
+            AutomationId = "GoBackButton"
+        };
+        goBackButton.Clicked += GoBack;
+
+        var grid = new Grid
+        {
+            RowDefinitions =
+    {
+        new RowDefinition { Height = new GridLength(1, GridUnitType.Star) },  // Row 0: for map
+        new RowDefinition { Height = GridLength.Auto }                         // Row 1: for button
+    }
+        };
+
+        grid.Children.Add(_map);
+        Grid.SetRow(_map, 0);
+
+        grid.Children.Add(goBackButton);
+        Grid.SetRow(goBackButton, 1);
+        Content = grid;
+
+        MoveMap();
+    }
+
+    private async void MoveMap()
+    {
+        await Task.Delay(1000).ConfigureAwait(false);
+
+        MainThread.BeginInvokeOnMainThread(() =>
+        {
+            var mapSpan = MapSpan.FromCenterAndRadius(
+                new Location(5, 5),
+                Distance.FromMeters(10000));
+
+            _map.MoveToRegion(mapSpan);
+        });
+    }
+
+    void GoBack(object sender, EventArgs e)
+    {
+        _map.Handler?.DisconnectHandler();
+        Navigation.PopAsync();
+    }
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue20612.cs

@@ -0,0 +1,27 @@
+#if TEST_FAILS_ON_WINDOWS
+//No Map control support in windows https://learn.microsoft.com/en-us/dotnet/maui/user-interface/controls/map?view=net-maui-9.0
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+public class Issue20612 : _IssuesUITest
+{
+	public Issue20612(TestDevice device) : base(device) { }
+
+	public override string Issue => "Disconnecting Map Handler causes Map to crash on second page entrance and moving to region.";
+
+	[Test]
+	[Category(UITestCategories.Maps)]
+	public void MapsShouldNotCrashWhenNavigationOccurs()
+	{
+		App.WaitForElement("MapButton");
+		App.Tap("MapButton");
+		App.WaitForElement("GoBackButton");
+		App.Tap("GoBackButton");
+		// second Navigation to Map page
+		App.WaitForElement("MapButton");
+		App.Tap("MapButton");
+	}
+}
+#endif

src/Core/maps/src/Handlers/Map/MapHandler.iOS.cs

@@ -13,7 +13,7 @@ public partial class MapHandler : ViewHandler<IMap, MauiMKMapView>
 
 		protected override MauiMKMapView CreatePlatformView()
 		{
-			return MapPool.Get() ?? new MauiMKMapView(this);
+			return MapPool.Get(this) ?? new MauiMKMapView(this);
 		}
 
 		protected override void ConnectHandler(MauiMKMapView platformView)

src/Core/maps/src/Platform/iOS/MapPool.cs

@@ -1,4 +1,5 @@
 using System.Collections.Concurrent;
+using Microsoft.Maui.Maps.Handlers;
 
 namespace Microsoft.Maui.Maps.Platform
 {
@@ -11,6 +12,14 @@ internal class MapPool
 
 		public static void Add(MauiMKMapView mapView) => Instance.Maps.Enqueue(mapView);
 
-		public static MauiMKMapView? Get() => Instance.Maps.TryDequeue(out MauiMKMapView? mapView) ? mapView : null;
+		public static MauiMKMapView? Get(IMapHandler mapHandler)
+		{
+			if (Instance.Maps.TryDequeue(out MauiMKMapView? mapView) && mapView is not null)
+			{
+				mapView.Handler = mapHandler;
+				return mapView;
+			}
+			return null;
+		}
 	}
 }

src/Core/maps/src/Platform/iOS/MauiMKMapView.cs

@@ -22,6 +22,22 @@ public MauiMKMapView(IMapHandler handler)
 			OverlayRenderer = GetViewForOverlayDelegate;
 		}
 
+		internal IMapHandler? Handler
+		{
+			get
+			{
+				_handlerRef.TryGetTarget(out var handler);
+				return handler;
+			}
+			set
+			{
+				if (value is not null)
+				{
+					_handlerRef = new WeakReference<IMapHandler>(value);
+				}
+			}
+		}
+
 		public override void MovedToWindow()
 		{
 			base.MovedToWindow();