Merge pull request #18791 from endragor/fix-ios-lifecycle

Proper focus in/out handling on iOS

platform/iphone/app_delegate.mm

@@ -709,21 +709,18 @@ static int frame_count = 0;
 	iphone_finish();
 };
 
-- (void)applicationDidEnterBackground:(UIApplication *)application {
-	///@TODO maybe add pause motionManager? and where would we unpause it?
+// When application goes to background (e.g. user switches to another app or presses Home),
+// then applicationWillResignActive -> applicationDidEnterBackground are called.
+// When user opens the inactive app again,
+// applicationWillEnterForeground -> applicationDidBecomeActive are called.
 
-	on_focus_out(view_controller, &is_focus_out);
-}
-
-- (void)applicationWillEnterForeground:(UIApplication *)application {
-	// OS::get_singleton()->get_main_loop()->notification(MainLoop::NOTIFICATION_WM_FOCUS_IN);
-	[view_controller.view startAnimation];
-}
+// There are cases when applicationWillResignActive -> applicationDidBecomeActive
+// sequence is called without the app going to background. For example, that happens
+// if you open the app list without switching to another app or open/close the
+// notification panel by swiping from the upper part of the screen.
 
 - (void)applicationWillResignActive:(UIApplication *)application {
-	// OS::get_singleton()->get_main_loop()->notification(MainLoop::NOTIFICATION_WM_FOCUS_OUT);
-	[view_controller.view
-					stopAnimation]; // FIXME: pause seems to be recommended elsewhere
+	on_focus_out(view_controller, &is_focus_out);
 }
 
 - (void)applicationDidBecomeActive:(UIApplication *)application {