add more comments and move to Controls

Author: mattleibow

src/Controls/src/Core/Label/Label.iOS.cs

@@ -36,12 +36,17 @@ public static void MapMaxLines(ILabelHandler handler, Label label)
 			handler.PlatformView?.UpdateMaxLines(label);
 		}
 
-		static void MapFormatting(ILabelHandler handler, Label label)
+		internal static void MapFormatting(ILabelHandler handler, Label label)
 		{
-			if (!IsPlainText(label))
-				return;
-
-			LabelHandler.MapFormatting(handler, label);
+			if (IsPlainText(label))
+			{
+				LabelHandler.MapFormatting(handler, label);
+			}
+			else
+			{
+				handler.UpdateValue(nameof(ILabel.TextColor));
+				handler.UpdateValue(nameof(ILabel.Font));
+			}
 		}
 
 		void RecalculateSpanPositions(Size size)

src/Controls/src/Core/Platform/iOS/Extensions/LabelExtensions.cs

@@ -14,7 +14,22 @@ public static void UpdateText(this UILabel platformLabel, Label label)
 			switch (label.TextType)
 			{
 				case TextType.Html:
-					platformLabel.UpdateTextHtml(label);
+					// NOTE: Setting HTML text this will crash with some sort of consistency error.
+					// https://github.com/dotnet/maui/issues/25946
+					// Here we have to dispatch back the the main queue to avoid the crash.
+					// This is observed with CarouselView 1 but not with 2, so hopefully this
+					// will be just disappear once we switch.
+					CoreFoundation.DispatchQueue.MainQueue.DispatchAsync(() =>
+					{
+						platformLabel.UpdateTextHtml(label);
+
+						if (label.Handler is LabelHandler labelHandler)
+							Label.MapFormatting(labelHandler, label);
+
+						// NOTE: Because we are updating text outside the normal layout
+						// pass, we need to invalidate the measure for the next pass.
+						label.InvalidateMeasure();
+					});
 					break;
 
 				default:

src/Core/src/Handlers/Label/LabelHandler.iOS.cs

@@ -81,11 +81,5 @@ public static void MapFormatting(ILabelHandler handler, ILabel label)
 			// so we need to make sure those are applied, too
 			handler.UpdateValue(nameof(ILabel.HorizontalTextAlignment));
 		}
-
-		internal static void ReapplyFormattingForHTMLLabel(ILabelHandler handler, ILabel label)
-		{
-			handler.UpdateValue(nameof(ILabel.TextColor));
-			handler.UpdateValue(nameof(ILabel.Font));
-		}
 	}
 }

src/Core/src/Platform/iOS/LabelExtensions.cs

@@ -88,14 +88,17 @@ internal static void UpdateTextHtml(this UILabel platformLabel, ILabel label)
 			};
 
 			NSError nsError = new();
-			CoreFoundation.DispatchQueue.MainQueue.DispatchAsync(() =>
-			{
-				platformLabel.AttributedText = new NSAttributedString(text, attr, ref nsError);
-				if (label.Handler is ILabelHandler labelHandler)
-					LabelHandler.ReapplyFormattingForHTMLLabel(labelHandler, label);
-					
-				label.InvalidateMeasure();
-			});
+
+			// NOTE: Sometimes this will crash with some sort of consistency error.
+			// https://github.com/dotnet/maui/issues/25946
+			// The caller should ensure that this extension is dispatched. We cannot
+			// do it here as we need to re-apply the formatting and we cannot call
+			// into Controls from Core.
+			// This is observed with CarouselView 1 but not with 2, so hopefully this
+			// will be just disappear once we switch.
+#pragma warning disable CS8601
+			platformLabel.AttributedText = new NSAttributedString(text, attr, ref nsError);
+#pragma warning restore CS8601
 		}
 
 		internal static void UpdateTextPlainText(this UILabel platformLabel, IText label)