[ios] use interfaceOrientation orientation on iOS 13 and above (#42846)

The UIApplication.statusBarOrientation is deprecated on iOS 9. The replacement is UIScene.interfaceOrientation, which is available on iOS 13 and above. See: https://developer.apple.com/documentation/uikit/uiapplication/1623026-statusbarorientation?language=objc

Part of flutter/flutter#128730

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

Author: Chris Yang

shell/platform/darwin/ios/framework/Source/FlutterViewController.mm

@@ -618,11 +618,19 @@ - (UIScreen*)mainScreenIfViewLoaded {
     if (self.viewIfLoaded == nil) {
       FML_LOG(WARNING) << "Trying to access the view before it is loaded.";
     }
-    return self.viewIfLoaded.window.windowScene.screen;
+    return [self windowSceneIfViewLoaded].screen;
   }
   return UIScreen.mainScreen;
 }
 
+- (UIWindowScene*)windowSceneIfViewLoaded {
+  if (self.viewIfLoaded == nil) {
+    FML_LOG(WARNING) << "Trying to access the view before it is loaded.";
+    return nil;
+  }
+  return self.viewIfLoaded.window.windowScene;
+}
+
 - (BOOL)loadDefaultSplashScreenView {
   NSString* launchscreenName =
       [[[NSBundle mainBundle] infoDictionary] objectForKey:@"UILaunchStoryboardName"];
@@ -1858,8 +1866,19 @@ - (void)performOrientationUpdate:(UIInterfaceOrientationMask)new_preferences {
         [self setNeedsUpdateOfSupportedInterfaceOrientations];
       }
     } else {
-      UIInterfaceOrientationMask currentInterfaceOrientation =
-          1 << [[UIApplication sharedApplication] statusBarOrientation];
+      UIInterfaceOrientationMask currentInterfaceOrientation;
+      if (@available(iOS 13.0, *)) {
+        UIWindowScene* windowScene = [self windowSceneIfViewLoaded];
+        if (!windowScene) {
+          // When the view is not loaded, it does not make sense to access the interface
+          // orientation, bail.
+          FML_LOG(WARNING) << "Trying to access the window scene before the view is loaded.";
+          return;
+        }
+        currentInterfaceOrientation = 1 << windowScene.interfaceOrientation;
+      } else {
+        currentInterfaceOrientation = 1 << [[UIApplication sharedApplication] statusBarOrientation];
+      }
       if (!(_orientationPreferences & currentInterfaceOrientation)) {
         [UIViewController attemptRotationToDeviceOrientation];
         // Force orientation switch if the current orientation is not allowed

shell/platform/darwin/ios/framework/Source/FlutterViewControllerTest.mm

@@ -1464,9 +1464,14 @@ - (void)orientationTestWithOrientationUpdate:(UIInterfaceOrientationMask)mask
       } else {
         OCMExpect([deviceMock setValue:@(resultingOrientation) forKey:@"orientation"]);
       }
-
-      OCMStub([mockApplication sharedApplication]).andReturn(mockApplication);
-      OCMStub([mockApplication statusBarOrientation]).andReturn(currentOrientation);
+      if (@available(iOS 13.0, *)) {
+        mockWindowScene = OCMPartialMock(realVC.view.window.windowScene);
+        OCMStub(((UIWindowScene*)mockWindowScene).interfaceOrientation)
+            .andReturn(currentOrientation);
+      } else {
+        OCMStub([mockApplication sharedApplication]).andReturn(mockApplication);
+        OCMStub([mockApplication statusBarOrientation]).andReturn(currentOrientation);
+      }
     }
 
     [realVC performOrientationUpdate:mask];

shell/platform/darwin/ios/framework/Source/FlutterViewController_Internal.h

@@ -65,6 +65,7 @@ typedef void (^FlutterKeyboardAnimationCallback)(fml::TimePoint);
 - (void)addInternalPlugins;
 - (void)deregisterNotifications;
 - (int32_t)accessibilityFlags;
+- (UIWindowScene*)windowSceneIfViewLoaded API_AVAILABLE(ios(13.0));
 
 @end