chore: Adjustments for URIs

src/Uno.UI/UI/Xaml/Controls/WebView/Core/CoreWebView2.cs

@@ -119,10 +119,23 @@ public partial class CoreWebView2
 		}
 	}
 
-	internal void RaiseNavigationStarting(string uri, out bool cancel)
+	internal void RaiseNavigationStarting(object navigationData, out bool cancel)
 	{
+		string? uriString = null;
+		if (navigationData is Uri uri)
+		{
+			uriString = uri.ToString();
+		}
+		else if (navigationData is string htmlContent)
+		{
+			// Convert to data URI string
+			var plainTextBytes = System.Text.Encoding.UTF8.GetBytes(htmlContent);
+			var base64String = System.Convert.ToBase64String(plainTextBytes);
+			uriString = string.Format(CultureInfo.InvariantCulture, DataUriFormatString, base64String);
+		}
+
 		var newNavigationId = Interlocked.Increment(ref _navigationId);
-		var args = new CoreWebView2NavigationStartingEventArgs((ulong)newNavigationId, uri);
+		var args = new CoreWebView2NavigationStartingEventArgs((ulong)newNavigationId, uriString);
 		NavigationStarting?.Invoke(this, args);
 
 		cancel = args.Cancel;

src/Uno.UI/UI/Xaml/Controls/WebView/Core/CoreWebView2NavigationStartingEventArgs.cs

@@ -9,7 +9,7 @@ namespace Microsoft.Web.WebView2.Core;
 /// </summary>
 public partial class CoreWebView2NavigationStartingEventArgs : EventArgs
 {
-	public CoreWebView2NavigationStartingEventArgs(ulong navigationId, string uri) =>
+	public CoreWebView2NavigationStartingEventArgs(ulong navigationId, string? uri) =>
 		(NavigationId, Uri) = (navigationId, uri);
 
 	/// <summary>
@@ -20,7 +20,7 @@ public partial class CoreWebView2NavigationStartingEventArgs : EventArgs
 	/// <summary>
 	/// Gets the URI of the requested navigation.
 	/// </summary>
-	public string Uri { get; }
+	public string? Uri { get; }
 
 	/// <summary>
 	/// Determines whether to cancel the navigation.

src/Uno.UI/UI/Xaml/Controls/WebView/Native/iOSmacOS/UnoWKWebView.iOSmacOS.cs

@@ -17,6 +17,7 @@ using Uno.UI.Extensions;
 using Windows.Foundation;
 using System.Collections.Generic;
 using System.Globalization;
+using System.Text;
 using System.Net;
 
 #if __IOS__
@@ -30,7 +31,7 @@ namespace Windows.UI.Xaml.Controls;
 
 public partial class UnoWKWebView : WKWebView, INativeWebView, IWKScriptMessageHandler
 #if __MACOS__
-	,IHasSizeThatFits
+	, IHasSizeThatFits
 #endif
 {
 	private CoreWebView2 _coreWebView;
@@ -81,7 +82,7 @@ public partial class UnoWKWebView : WKWebView, INativeWebView, IWKScriptMessageH
 		var height = Math.Min(availableSize.Height, FittingSize.Height);
 		var width = Math.Min(availableSize.Width, FittingSize.Width);
 		return new CGSize(width, height);
-	} 
+	}
 #endif
 
 
@@ -210,7 +211,7 @@ public partial class UnoWKWebView : WKWebView, INativeWebView, IWKScriptMessageH
 		}
 		else
 		{
-			RaiseNavigationStarting(targetString, out var cancel);
+			RaiseNavigationStarting(target, out var cancel);
 
 			if (!cancel)
 			{
@@ -307,7 +308,8 @@ public partial class UnoWKWebView : WKWebView, INativeWebView, IWKScriptMessageH
 		};
 		alert.AddButton(OkString);
 		alert.AddButton(CancelString);
-		alert.BeginSheetForResponse(webview.Window, (result) => {
+		alert.BeginSheetForResponse(webview.Window, (result) =>
+		{
 			var okButtonClicked = result == 1000;
 			completionHandler(okButtonClicked);
 		});
@@ -352,7 +354,8 @@ public partial class UnoWKWebView : WKWebView, INativeWebView, IWKScriptMessageH
 		alert.AccessoryView = textField;
 		alert.AddButton(OkString);
 		alert.AddButton(CancelString);
-		alert.BeginSheetForResponse(webview.Window, (result) => {
+		alert.BeginSheetForResponse(webview.Window, (result) =>
+		{
 			var okButtonClicked = result == 1000;
 			completionHandler(okButtonClicked ? textField.StringValue : null);
 		});
@@ -376,9 +379,7 @@ public partial class UnoWKWebView : WKWebView, INativeWebView, IWKScriptMessageH
 
 		_isCancelling = false;
 
-		RaiseNavigationStarting(CoreWebView2.BlankUrl, out var cancel); //TODO:MZ: For HTML content 		var plainTextBytes = System.Text.Encoding.UTF8.GetBytes(htmlContent);
-																					 //var base64String = System.Convert.ToBase64String(plainTextBytes);
-																					 //var htmlUri = new Uri(string.Format(CultureInfo.InvariantCulture, DataUriFormatString, base64String));
+		RaiseNavigationStarting(targetUrl ?? _lastNavigationData, out var cancel); //TODO:MZ: For HTML content
 
 		if (cancel)
 		{
@@ -392,9 +393,9 @@ public partial class UnoWKWebView : WKWebView, INativeWebView, IWKScriptMessageH
 		return cancel;
 	}
 
-	private void RaiseNavigationStarting(string uriString, out bool cancel)
+	private void RaiseNavigationStarting(object navigationData, out bool cancel)
 	{
-		if (uriString == null)
+		if (navigationData is null)
 		{
 			// This ase should not happen when navigating normally using http requests.
 			// This is to stop a scenario where the webview is initialized without having a source
@@ -402,7 +403,7 @@ public partial class UnoWKWebView : WKWebView, INativeWebView, IWKScriptMessageH
 			return;
 		}
 
-		if (Uri.TryCreate(uriString, UriKind.Absolute, out var uri) && uri.Scheme.Equals(Uri.UriSchemeMailto, StringComparison.OrdinalIgnoreCase))
+		if (navigationData is Uri uri && uri.Scheme.Equals(Uri.UriSchemeMailto, StringComparison.OrdinalIgnoreCase))
 		{
 #if __IOS__
 			ParseUriAndLauchMailto(uri);
@@ -414,7 +415,7 @@ public partial class UnoWKWebView : WKWebView, INativeWebView, IWKScriptMessageH
 		}
 
 		_coreWebView.SetHistoryProperties(CanGoBack, CanGoForward);
-		_coreWebView.RaiseNavigationStarting(uriString, out cancel);
+		_coreWebView.RaiseNavigationStarting(navigationData, out cancel);
 	}
 
 	private void RaiseNavigationCompleted(Uri uri, bool isSuccess, int httpStatusCode, CoreWebView2WebErrorStatus errorStatus)