Fix duplicate state container view states

src/CommunityToolkit.Maui.UnitTests/Layouts/StateContainerTests.cs

@@ -56,12 +56,12 @@ public StateContainerTests()
 
 		controller = new StateContainerController(layout)
 		{
-			StateViews = StateContainer.GetStateViews(layout)
+			StateViews = [..StateContainer.GetStateViews(layout)]
 		};
 
 		gridController = new StateContainerController(grid)
 		{
-			StateViews = StateContainer.GetStateViews(grid)
+			StateViews = [..StateContainer.GetStateViews(grid)]
 		};
 	}
 
@@ -594,12 +594,37 @@ public void EnsureDefaults()
 		var stackLayout = new StackLayout();
 
 		// Act Assert
-		Assert.Equal(StateContainerDefaults.StateViews, StateContainer.GetStateViews(stackLayout));
+		Assert.Equal([], StateContainer.GetStateViews(stackLayout));
+		Assert.Empty(StateContainer.GetStateViews(stackLayout));
 		Assert.Equal(StateContainerDefaults.CurrentState, StateContainer.GetCurrentState(stackLayout));
 		Assert.Equal(StateContainerDefaults.CanStateChange, StateContainer.GetCanStateChange(stackLayout));
 		Assert.Equal(StateViewDefaults.StateKey, StateView.GetStateKey(stackLayout));
 	}
 
+	[Fact]
+	public void EnsureLayoutControllerIsUniquePerLayout()
+	{
+		// Arrange
+		var grid1 = new Grid();
+		var grid2 = new Grid();
+
+		// Act
+
+		StateContainer.SetStateViews(grid1, stateViews);
+		StateContainer.SetStateViews(grid2, 
+		[
+			new Label() { Text = "Test" },
+		]);
+
+		var grid1StateViews = StateContainer.GetStateViews(grid1);
+		var grid2StateViews = StateContainer.GetStateViews(grid2);
+
+		// Assert
+		Assert.NotEqual(grid1StateViews, grid2StateViews);
+		Assert.Equal(stateViews.Count, grid1StateViews.Count);
+		Assert.Single(StateContainer.GetStateViews(grid2));
+	}
+
 	sealed class ViewModel : INotifyPropertyChanged
 	{
 		public bool CanChangeState

src/CommunityToolkit.Maui/Layouts/StateContainer/StateContainer.shared.cs

@@ -180,7 +180,7 @@ static StateContainerController ContainerControllerCreator(BindableObject bindab
 
 		return new StateContainerController(layoutView)
 		{
-			StateViews = GetStateViews(layoutView)
+			StateViews = [..GetStateViews(layoutView)]
 		};
 	}
 
@@ -192,7 +192,7 @@ static void ValidateCanStateChange(in BindableObject bindable)
 		}
 	}
 
-	static IList<View> CreateDefaultStateViewsProperty(BindableObject bindable) => StateContainerDefaults.StateViews;
+	static IList<View> CreateDefaultStateViewsProperty(BindableObject bindable) => [];
 }
 
 /// <summary>

src/CommunityToolkit.Maui/Layouts/StateContainer/StateContainerController.shared.cs

@@ -3,23 +3,21 @@
 /// <summary>
 /// StateContainer Controller
 /// </summary>
-sealed class StateContainerController
+/// <remarks>
+/// Initialize <see cref="StateContainerController"/> with a <see cref="Layout"/>
+/// </remarks>
+/// <param name="layout"></param>
+sealed class StateContainerController(Layout layout)
 {
-	readonly WeakReference<Layout> layoutWeakReference;
+	readonly WeakReference<Layout> layoutWeakReference = new(layout);
 
 	string? previousState;
 	List<IView> originalContent = Enumerable.Empty<IView>().ToList();
 
-	/// <summary>
-	/// Initialize <see cref="StateContainerController"/> with a <see cref="Layout"/>
-	/// </summary>
-	/// <param name="layout"></param>
-	public StateContainerController(Layout layout) => layoutWeakReference = new WeakReference<Layout>(layout);
-
 	/// <summary>
 	/// The StateViews defined in the StateContainer.
 	/// </summary>
-	public required IList<View> StateViews { get; set; }
+	public required IReadOnlyList<View> StateViews { get; init; }
 
 	/// <summary>
 	/// Display the default content.

src/CommunityToolkit.Maui/Primitives/StateContainerDefaults.shared.cs

@@ -4,5 +4,4 @@ static class StateContainerDefaults
 {
 	public const string? CurrentState = null;
 	public const bool CanStateChange = true;
-	public static IList<View> StateViews { get; } = [];
 }