Fix StrokeDashArray on Border does not reset when set to null

src/Controls/tests/TestCases.HostApp/Issues/Issue29898.cs

@@ -0,0 +1,54 @@
+using System.Collections.ObjectModel;
+
+namespace Maui.Controls.Sample.Issues;
+[Issue(IssueTracker.Github, 29898, "[iOS, macOS] StrokeDashArray on Border does not reset when set to null", PlatformAffected.iOS)]
+public class Issue29898 : ContentPage
+{
+	public Issue29898()
+	{
+		var border = new Border
+		{
+			HeightRequest = 200,
+			WidthRequest = 200,
+			BackgroundColor = Colors.LightGray,
+			Stroke = Colors.Blue,
+			StrokeThickness = 5,
+			StrokeDashArray = new DoubleCollection { 10, 5 }
+		};
+
+		var button = new Button
+		{
+			Text = "Clear StrokeDashArray",
+			AutomationId = "ClearDashButton",
+			HorizontalOptions = LayoutOptions.Center
+		};
+
+		var button2 = new Button
+		{
+			Text = "Set StrokeDashArray",
+			AutomationId = "SetDashButton",
+			HorizontalOptions = LayoutOptions.Center
+		};
+
+		button.Clicked += (s, e) =>
+		{
+			border.StrokeDashArray = null;
+		};
+
+		button2.Clicked += (s, e) =>
+		{
+			border.StrokeDashArray = new DoubleCollection { 5, 2 };
+		};
+
+		var layout = new VerticalStackLayout
+		{
+			Spacing = 25,
+			Padding = new Thickness(30, 60, 30, 30),
+			VerticalOptions = LayoutOptions.Center,
+			Children = { border, button, button2 }
+		};
+
+		Content = layout;
+	}
+
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue29898.cs

@@ -0,0 +1,32 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue29898 : _IssuesUITest
+{
+	public override string Issue => "[iOS, macOS] StrokeDashArray on Border does not reset when set to null";
+
+	public Issue29898(TestDevice device)
+	: base(device)
+	{ }
+
+	[Test, Order(1)]
+	[Category(UITestCategories.Border)]
+	public void VerifyBorderWithNullStrokeDashArray()
+	{
+		App.WaitForElement("ClearDashButton");
+		App.Tap("ClearDashButton");
+		VerifyScreenshot();
+	}
+
+	[Test, Order(2)]
+	[Category(UITestCategories.Border)]
+	public void VerifyBorderWithStrokeDashArrayValue()
+	{
+		App.WaitForElement("SetDashButton");
+		App.Tap("SetDashButton");
+		VerifyScreenshot();
+	}
+}

src/Core/src/Platform/Windows/BorderExtensions.cs

@@ -75,6 +75,10 @@ public static void UpdateStrokeDashPattern(this Path borderPath, float[]? border
 					borderPath.StrokeDashArray.Add(value);
 				}
 			}
+			else if (borderDashArray is null || borderDashArray.Length == 0)
+			{
+				borderPath.StrokeDashArray = null;
+			}
 		}
 
 		public static void UpdateBorderDashOffset(this Path borderPath, double borderDashOffset)

src/Core/src/Platform/Windows/StrokeExtensions.cs

@@ -30,9 +30,6 @@ public static void UpdateStrokeDashPattern(this ContentPanel platformView, IBord
 		{
 			var strokeDashPattern = border.StrokeDashPattern;
 
-			if (strokeDashPattern == null)
-				return;
-
 			platformView.BorderPath?.UpdateStrokeDashPattern(strokeDashPattern);
 		}
 

src/Core/src/Platform/iOS/MauiCALayer.cs

@@ -250,6 +250,10 @@ public void SetBorderDash(float[]? borderDashArray, double borderDashOffset)
 
 				_strokeDash = dashArray;
 			}
+			else if (borderDashArray is null || borderDashArray.Length == 0)
+			{
+				_strokeDash = null;
+			}
 
 			SetNeedsDisplay();
 		}