use composition renderer only on ios.

src/Linux/Avalonia.LinuxFramebuffer/FramebufferToplevelImpl.cs

@@ -7,6 +7,7 @@ using Avalonia.LinuxFramebuffer.Input;
 using Avalonia.LinuxFramebuffer.Output;
 using Avalonia.Platform;
 using Avalonia.Rendering;
+using Avalonia.Rendering.Composition;
 
 namespace Avalonia.LinuxFramebuffer
 {
@@ -32,7 +33,7 @@ namespace Avalonia.LinuxFramebuffer
         {
             var factory = AvaloniaLocator.Current.GetService<IRendererFactory>();
             var renderLoop = AvaloniaLocator.Current.GetService<IRenderLoop>();
-            return factory?.Create(root, renderLoop) ?? new DeferredRenderer(root, renderLoop);
+            return factory?.Create(root, renderLoop) ?? new CompositingRenderer(root, new Compositor(renderLoop, null));
         }
 
         public void Dispose()

src/iOS/Avalonia.iOS/AvaloniaView.cs

@@ -10,6 +10,7 @@ using Avalonia.iOS.Storage;
 using Avalonia.Platform;
 using Avalonia.Platform.Storage;
 using Avalonia.Rendering;
+using Avalonia.Rendering.Composition;
 using CoreAnimation;
 using Foundation;
 using ObjCRuntime;
@@ -63,8 +64,8 @@ namespace Avalonia.iOS
                 // No-op
             }
 
-            public IRenderer CreateRenderer(IRenderRoot root) => new DeferredRenderer(root,
-                AvaloniaLocator.Current.GetService<IRenderLoop>());
+            public IRenderer CreateRenderer(IRenderRoot root) => new CompositingRenderer(root, Platform.Compositor);
+                    
 
             public void Invalidate(Rect rect)
             {

src/iOS/Avalonia.iOS/Platform.cs

@@ -6,6 +6,7 @@ using Avalonia.Input.Platform;
 using Avalonia.OpenGL;
 using Avalonia.Platform;
 using Avalonia.Rendering;
+using Avalonia.Rendering.Composition;
 
 namespace Avalonia
 {
@@ -26,6 +27,8 @@ namespace Avalonia.iOS
     {
         public static EaglFeature GlFeature;
         public static DisplayLinkTimer Timer;
+        internal static Compositor Compositor { get; private set; }
+        
         class PlatformSettings : IPlatformSettings
         {
             /// <inheritdoc cref="IPlatformSettings.TouchDoubleClickSize"/>
@@ -57,6 +60,10 @@ namespace Avalonia.iOS
                 .Bind<IRenderTimer>().ToConstant(Timer)
                 .Bind<IPlatformThreadingInterface>().ToConstant(new PlatformThreadingInterface())
                 .Bind<IKeyboardDevice>().ToConstant(keyboard);
+
+                Compositor = new Compositor(
+                    AvaloniaLocator.Current.GetRequiredService<IRenderLoop>(),
+                    AvaloniaLocator.Current.GetService<IPlatformOpenGlInterface>());
         }