Make game unfocused on incoming call

osu.Framework.iOS/IOSCallObserver.cs

@@ -0,0 +1,44 @@
+// Copyright (c) ppy Pty Ltd <[email protected]>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using System.Linq;
+using CallKit;
+using Foundation;
+
+namespace osu.Framework.iOS
+{
+    internal class IOSCallObserver : NSObject, ICXCallObserverDelegate
+    {
+        private readonly Action onCall;
+        private readonly Action onCallEnded;
+
+        private readonly CXCallController callController;
+
+        public IOSCallObserver(Action onCall, Action onCallEnded)
+        {
+            this.onCall = onCall;
+            this.onCallEnded = onCallEnded;
+
+            callController = new CXCallController();
+            callController.CallObserver.SetDelegate(this, null);
+
+            if (callController.CallObserver.Calls.Any(c => !c.HasEnded))
+                onCall();
+        }
+
+        public void CallChanged(CXCallObserver callObserver, CXCall call)
+        {
+            if (!call.HasEnded)
+                onCall();
+            else
+                onCallEnded();
+        }
+
+        protected override void Dispose(bool disposing)
+        {
+            callController.Dispose();
+            base.Dispose(disposing);
+        }
+    }
+}

osu.Framework.iOS/IOSWindow.cs

@@ -11,6 +11,7 @@
 using osu.Framework.Graphics;
 using osu.Framework.Platform;
 using osu.Framework.Platform.SDL3;
+using SDL;
 using static SDL.SDL3;
 using UIKit;
 
@@ -22,6 +23,8 @@ internal class IOSWindow : SDL3MobileWindow
 
         public UIWindow UIWindow => uiWindow!;
 
+        private IOSCallObserver callObserver;
+
         public override Size Size
         {
             get => base.Size;
@@ -50,8 +53,53 @@ public override void Create()
 
             var appDelegate = (GameApplicationDelegate)UIApplication.SharedApplication.Delegate;
             appDelegate.DragDrop += TriggerDragDrop;
+
+            // osu! cannot operate when a call takes place, as the audio is completely cut from the game, making it behave in unexpected manner.
+            // while this is o!f code, it's simpler to do this here rather than in osu!.
+            // we can reconsider this if there are framework consumers which find this behaviour undesirable.
+            callObserver = new IOSCallObserver(onCall, onCallEnded);
+            updateFocused();
         }
 
+        private bool appInForeground;
+        private bool inCall;
+
+        protected override void HandleEvent(SDL_Event e)
+        {
+            switch (e.Type)
+            {
+                case SDL_EventType.SDL_EVENT_WINDOW_MINIMIZED:
+                case SDL_EventType.SDL_EVENT_WINDOW_FOCUS_LOST:
+                    appInForeground = false;
+                    updateFocused();
+                    break;
+
+                case SDL_EventType.SDL_EVENT_WINDOW_RESTORED:
+                case SDL_EventType.SDL_EVENT_WINDOW_FOCUS_GAINED:
+                    appInForeground = true;
+                    updateFocused();
+                    break;
+
+                default:
+                    base.HandleEvent(e);
+                    break;
+            }
+        }
+
+        private void onCall()
+        {
+            inCall = true;
+            updateFocused();
+        }
+
+        private void onCallEnded()
+        {
+            inCall = false;
+            updateFocused();
+        }
+
+        private void updateFocused() => Focused = appInForeground && !inCall;
+
         protected override unsafe void RunMainLoop()
         {
             // Delegate running the main loop to CADisplayLink.