Update App.axaml.cs (#9421)

* Update App.axaml.cs

* Update App.axaml.cs

* Create MacOSAppHelper.cs

* Update App.axaml.cs

Removed unused macOS activation policy methods and constants.

* Update and rename MacOSAppHelper.cs to MacAppUtils.cs

* Update App.axaml.cs

v2rayN/v2rayN.Desktop/App.axaml.cs

@@ -1,3 +1,4 @@
+using v2rayN.Desktop.Common;
 using v2rayN.Desktop.Views;
 
 namespace v2rayN.Desktop;
@@ -24,11 +25,34 @@ public partial class App : Application
 
             desktop.Exit += OnExit;
             desktop.MainWindow = new MainWindow();
+
+            if (OperatingSystem.IsMacOS())
+            {
+                Current?.TryGetFeature<IActivatableLifetime>()?.Activated += OnMacOSActivated;
+            }
         }
 
         base.OnFrameworkInitializationCompleted();
     }
 
+    private void OnMacOSActivated(object? sender, ActivatedEventArgs args)
+    {
+        if (args.Kind != ActivationKind.Reopen)
+        {
+            return;
+        }
+
+        Dispatcher.UIThread.Post(() =>
+        {
+            ((ApplicationLifetime as IClassicDesktopStyleApplicationLifetime)?.MainWindow as MainWindow)?.ShowHideWindow(true);
+
+            if (!AppManager.Instance.Config.UiItem.MacOSShowInDock)
+            {
+                MacAppUtils.SetActivationPolicyAccessory();
+            }
+        });
+    }
+
     private void CurrentDomain_UnhandledException(object sender, UnhandledExceptionEventArgs e)
     {
         if (e.ExceptionObject != null)

v2rayN/v2rayN.Desktop/Common/MacAppUtils.cs

@@ -0,0 +1,27 @@
+using System.Runtime.InteropServices;
+
+namespace v2rayN.Desktop.Common;
+
+internal static class MacAppUtils
+{
+    private const string LibObjC = "/usr/lib/libobjc.dylib";
+    private const nint ActivationPolicyAccessory = 1;
+
+    public static void SetActivationPolicyAccessory()
+        => objc_msgSend(
+            objc_msgSend(objc_getClass("NSApplication"), sel_registerName("sharedApplication")),
+            sel_registerName("setActivationPolicy:"),
+            ActivationPolicyAccessory);
+
+    [DllImport(LibObjC)]
+    private static extern nint objc_getClass(string name);
+
+    [DllImport(LibObjC)]
+    private static extern nint sel_registerName(string name);
+
+    [DllImport(LibObjC, EntryPoint = "objc_msgSend")]
+    private static extern nint objc_msgSend(nint receiver, nint selector);
+
+    [DllImport(LibObjC, EntryPoint = "objc_msgSend")]
+    private static extern void objc_msgSend(nint receiver, nint selector, nint argument);
+}