use ime api to hide and show osk.

src/iOS/Avalonia.iOS/AvaloniaUIResponder.cs

@@ -1,6 +1,56 @@
+using Foundation;
+using ObjCRuntime;
+using UIKit;
+using Avalonia.Input.TextInput;
+
 namespace Avalonia.iOS;
 
-public class AvaloniaUIResponder
+[Adopts("UIKeyInput")]
+public partial class AvaloniaView : ITextInputMethodImpl
 {
-    
+    public override bool CanResignFirstResponder => true;
+    public override bool CanBecomeFirstResponder => true;
+    public override bool CanBecomeFocused => true;
+
+    [Export("hasText")] public bool HasText => false;
+
+    [Export("insertText:")]
+    public void InsertText(string text)
+    {
+        
+    }
+
+    [Export("deleteBackward")]
+    public void DeleteBackward()
+    {
+    }
+
+    void ITextInputMethodImpl.SetActive(bool active)
+    {
+        if (active)
+        {
+            var isFr = IsFirstResponder;
+            var next = NextResponder;
+            var result = BecomeFirstResponder();
+        }
+        else
+        {
+            ResignFirstResponder();
+        }
+    }
+
+    void ITextInputMethodImpl.SetCursorRect(Rect rect)
+    {
+        
+    }
+
+    void ITextInputMethodImpl.SetOptions(TextInputOptionsQueryEventArgs options)
+    {
+        
+    }
+
+    void ITextInputMethodImpl.Reset()
+    {
+        
+    }
 }

src/iOS/Avalonia.iOS/AvaloniaView.cs

@@ -2,12 +2,13 @@ using System;
 using System.Collections.Generic;
 using Avalonia.Controls;
 using Avalonia.Controls.Embedding;
+using Avalonia.Controls.Platform;
 using Avalonia.Input;
 using Avalonia.Input.Raw;
+using Avalonia.Input.TextInput;
 using Avalonia.Platform;
 using Avalonia.Rendering;
 using CoreAnimation;
-using CoreGraphics;
 using Foundation;
 using ObjCRuntime;
 using OpenGLES;
@@ -42,7 +43,7 @@ namespace Avalonia.iOS
             MultipleTouchEnabled = true;
         }
 
-        internal class TopLevelImpl : ITopLevelImpl
+        internal class TopLevelImpl : ITopLevelImplWithTextInputMethod
         {
             private readonly AvaloniaView _view;
             public AvaloniaView View => _view;
@@ -109,6 +110,8 @@ namespace Avalonia.iOS
 
             public AcrylicPlatformCompensationLevels AcrylicCompensationLevels { get; } =
                 new AcrylicPlatformCompensationLevels();
+
+            public ITextInputMethodImpl? TextInputMethod => _view;
         }
 
         [Export("layerClass")]