[iOS] Add darwin_extension_safe flag and use UIScene api when buildin…

…g for extensions (#43449) iOS extensions forbids the usage of UIApplication.sharedApplication. This PR refactors the engine to use UISceneAPI when darwin_extension_safe flag is on. Using UISceneAPI can help avoid the usage of `UIApplication.sharedApplication` as much as possible. This PR also added a new `_extension_safe` variant for the engine build so all the logic with the `darwin_extension_safe` flag is on can be tested separately. This PR doesn't enable the engine to build for the extension even when darwin_extension_safe is true. part of flutter/flutter#124289 There are several issues related to UIApplication life cycle and I manually tested they still work with the scene API: [C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style
flutter · Aug 1, 2023 · d5f6b00 · d5f6b00
1 parent 10a1f9c
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diff --git a/ci/builders/mac_unopt.json b/ci/builders/mac_unopt.json
@@ -223,6 +223,77 @@
                     "script": "flutter/testing/scenario_app/run_ios_tests.sh"
                 }
 
+            ]
+        },
+        {
+            "archives": [
+                {
+                    "base_path": "out/ios_debug_sim_arm64_extension_safe/zip_archives/",
+                    "type": "gcs",
+                    "include_paths": [
+                    ],
+                    "name": "ios_debug_sim_arm64_extension_safe"
+                }
+            ],
+            "properties": {
+                "$flutter/osx_sdk": {
+                    "runtime_versions": [
+                        "ios-16-4_14e300c",
+                        "ios-16-2_14c18"
+                    ],
+                    "sdk_version": "14e300c"
+                }
+            },
+            "drone_dimensions": [
+                "device_type=none",
+                "os=Mac-12",
+                "cpu=arm64"
+            ],
+            "gclient_variables": {
+                "download_android_deps": false
+            },
+            "gn": [
+                "--ios",
+                "--runtime-mode",
+                "debug",
+                "--simulator",
+                "--no-lto",
+                "--force-mac-arm64",
+                "--simulator-cpu",
+                "arm64",
+                "--darwin-extension-safe"
+            ],
+            "name": "ios_debug_sim_arm64_extension_safe",
+            "ninja": {
+                "config": "ios_debug_sim_arm64_extension_safe",
+                "targets": [
+                    "flutter/testing/scenario_app",
+                    "flutter/shell/platform/darwin/ios:ios_test_flutter"
+                ]
+            },
+            "tests": [
+                {
+                    "language": "python3",
+                    "name": "Tests for ios_debug_sim_arm64_extension_safe",
+                    "parameters": [
+                        "--variant",
+                        "ios_debug_sim_arm64_extension_safe",
+                        "--type",
+                        "objc",
+                        "--engine-capture-core-dump",
+                        "--ios-variant",
+                        "ios_debug_sim_arm64_extension_safe"
+                    ],
+                    "script": "flutter/testing/run_tests.py"
+                },
+                {
+                    "name": "Scenario App Integration Tests",
+                    "parameters": [
+                        "ios_debug_sim_arm64_extension_safe"
+                    ],
+                    "script": "flutter/testing/scenario_app/run_ios_tests.sh"
+                }
+
             ]
         }
     ]

diff --git a/common/config.gni b/common/config.gni
@@ -22,6 +22,12 @@ declare_args() {
 
   # Whether to include backtrace support.
   enable_backtrace = true
+
+  # Whether to include --fapplication-extension when build iOS framework.
+  # This is currently a test flag and does not work properly.
+  #TODO(cyanglaz): Remove above comment about test flag when the entire iOS embedder supports app extension
+  #https://github.com/flutter/flutter/issues/124289
+  darwin_extension_safe = false
 }
 
 # feature_defines_list ---------------------------------------------------------

diff --git a/shell/platform/darwin/ios/BUILD.gn b/shell/platform/darwin/ios/BUILD.gn
@@ -44,6 +44,9 @@ source_set("flutter_framework_source_arc") {
   cflags_objcc = flutter_cflags_objcc_arc
 
   defines = [ "FLUTTER_FRAMEWORK=1" ]
+  if (darwin_extension_safe) {
+    defines += [ "APPLICATION_EXTENSION_API_ONLY=1" ]
+  }
   allow_circular_includes_from = [ ":flutter_framework_source" ]
   deps = [
     ":flutter_framework_source",
@@ -153,6 +156,9 @@ source_set("flutter_framework_source") {
   sources += _flutter_framework_headers
 
   defines = [ "FLUTTER_FRAMEWORK=1" ]
+  if (darwin_extension_safe) {
+    defines += [ "APPLICATION_EXTENSION_API_ONLY=1" ]
+  }
 
   if (shell_enable_metal) {
     sources += [
@@ -249,6 +255,10 @@ source_set("ios_test_flutter_mrc") {
   if (shell_enable_vulkan) {
     deps += [ "//flutter/vulkan" ]
   }
+
+  if (darwin_extension_safe) {
+    defines = [ "APPLICATION_EXTENSION_API_ONLY=1" ]
+  }
 }
 
 shared_library("ios_test_flutter") {
@@ -312,6 +322,10 @@ shared_library("ios_test_flutter") {
     ":ios_gpu_configuration_config",
     "//flutter:config",
   ]
+
+  if (darwin_extension_safe) {
+    defines = [ "APPLICATION_EXTENSION_API_ONLY=1" ]
+  }
 }
 
 shared_library("create_flutter_framework_dylib") {

diff --git a/shell/platform/darwin/ios/framework/Source/FlutterEngine.mm b/shell/platform/darwin/ios/framework/Source/FlutterEngine.mm
@@ -225,22 +225,44 @@ - (instancetype)initWithName:(NSString*)labelPrefix
                  name:UIApplicationDidReceiveMemoryWarningNotification
                object:nil];
 
+#if APPLICATION_EXTENSION_API_ONLY
+  if (@available(iOS 13.0, *)) {
+    [self setUpSceneLifecycleNotifications:center];
+  } else {
+    [self setUpApplicationLifecycleNotifications:center];
+  }
+#else
+  [self setUpApplicationLifecycleNotifications:center];
+#endif
+
   [center addObserver:self
-             selector:@selector(applicationWillEnterForeground:)
-                 name:UIApplicationWillEnterForegroundNotification
+             selector:@selector(onLocaleUpdated:)
+                 name:NSCurrentLocaleDidChangeNotification
                object:nil];
 
+  return self;
+}
+
+- (void)setUpSceneLifecycleNotifications:(NSNotificationCenter*)center API_AVAILABLE(ios(13.0)) {
   [center addObserver:self
-             selector:@selector(applicationDidEnterBackground:)
-                 name:UIApplicationDidEnterBackgroundNotification
+             selector:@selector(sceneWillEnterForeground:)
+                 name:UISceneWillEnterForegroundNotification
                object:nil];
-
   [center addObserver:self
-             selector:@selector(onLocaleUpdated:)
-                 name:NSCurrentLocaleDidChangeNotification
+             selector:@selector(sceneDidEnterBackground:)
+                 name:UISceneDidEnterBackgroundNotification
                object:nil];
+}
 
-  return self;
+- (void)setUpApplicationLifecycleNotifications:(NSNotificationCenter*)center {
+  [center addObserver:self
+             selector:@selector(applicationWillEnterForeground:)
+                 name:UIApplicationWillEnterForegroundNotification
+               object:nil];
+  [center addObserver:self
+             selector:@selector(applicationDidEnterBackground:)
+                 name:UIApplicationDidEnterBackgroundNotification
+               object:nil];
 }
 
 - (void)recreatePlatformViewController {
@@ -856,8 +878,20 @@ - (BOOL)createShell:(NSString*)entrypoint
                                     _threadHost->io_thread->GetTaskRunner()          // io
   );
 
+#if APPLICATION_EXTENSION_API_ONLY
+  if (@available(iOS 13.0, *)) {
+    _isGpuDisabled = self.viewController.windowSceneIfViewLoaded.activationState ==
+                     UISceneActivationStateBackground;
+  } else {
+    // [UIApplication sharedApplication API is not available for app extension.
+    // We intialize the shell assuming the GPU is required.
+    _isGpuDisabled = NO;
+  }
+#else
   _isGpuDisabled =
       [UIApplication sharedApplication].applicationState == UIApplicationStateBackground;
+#endif
+
   // Create the shell. This is a blocking operation.
   std::unique_ptr<flutter::Shell> shell = flutter::Shell::Create(
       /*platform_data=*/platformData,
@@ -1302,11 +1336,29 @@ - (NSObject*)valuePublishedByPlugin:(NSString*)pluginKey {
 
 #pragma mark - Notifications
 
+#if APPLICATION_EXTENSION_API_ONLY
+- (void)sceneWillEnterForeground:(NSNotification*)notification API_AVAILABLE(ios(13.0)) {
+  [self flutterWillEnterForeground:notification];
+}
+
+- (void)sceneDidEnterBackground:(NSNotification*)notification API_AVAILABLE(ios(13.0)) {
+  [self flutterDidEnterBackground:notification];
+}
+#else
 - (void)applicationWillEnterForeground:(NSNotification*)notification {
-  [self setIsGpuDisabled:NO];
+  [self flutterWillEnterForeground:notification];
 }
 
 - (void)applicationDidEnterBackground:(NSNotification*)notification {
+  [self flutterDidEnterBackground:notification];
+}
+#endif
+
+- (void)flutterWillEnterForeground:(NSNotification*)notification {
+  [self setIsGpuDisabled:NO];
+}
+
+- (void)flutterDidEnterBackground:(NSNotification*)notification {
   [self setIsGpuDisabled:YES];
   [self notifyLowMemory];
 }

diff --git a/shell/platform/darwin/ios/framework/Source/FlutterEngineTest.mm b/shell/platform/darwin/ios/framework/Source/FlutterEngineTest.mm
@@ -9,6 +9,7 @@
 #import <objc/runtime.h>
 
 #import "flutter/common/settings.h"
+#include "flutter/fml/synchronization/sync_switch.h"
 #import "flutter/shell/platform/darwin/common/framework/Headers/FlutterMacros.h"
 #import "flutter/shell/platform/darwin/ios/framework/Source/FlutterBinaryMessengerRelay.h"
 #import "flutter/shell/platform/darwin/ios/framework/Source/FlutterDartProject_Internal.h"
@@ -341,4 +342,62 @@ - (void)testFlutterEngineUpdatesDisplays {
   OCMVerify(times(2), [mockEngine updateDisplays]);
 }
 
+- (void)testLifeCycleNotificationDidEnterBackground {
+  FlutterDartProject* project = [[FlutterDartProject alloc] init];
+  FlutterEngine* engine = [[FlutterEngine alloc] initWithName:@"foobar" project:project];
+  [engine run];
+  NSNotification* sceneNotification =
+      [NSNotification notificationWithName:UISceneDidEnterBackgroundNotification
+                                    object:nil
+                                  userInfo:nil];
+  NSNotification* applicationNotification =
+      [NSNotification notificationWithName:UIApplicationDidEnterBackgroundNotification
+                                    object:nil
+                                  userInfo:nil];
+  id mockEngine = OCMPartialMock(engine);
+  [[NSNotificationCenter defaultCenter] postNotification:sceneNotification];
+  [[NSNotificationCenter defaultCenter] postNotification:applicationNotification];
+#if APPLICATION_EXTENSION_API_ONLY
+  OCMVerify(times(1), [mockEngine sceneDidEnterBackground:[OCMArg any]]);
+#else
+  OCMVerify(times(1), [mockEngine applicationDidEnterBackground:[OCMArg any]]);
+#endif
+  XCTAssertTrue(engine.isGpuDisabled);
+  bool switch_value = false;
+  [engine shell].GetIsGpuDisabledSyncSwitch()->Execute(
+      fml::SyncSwitch::Handlers().SetIfTrue([&] { switch_value = true; }).SetIfFalse([&] {
+        switch_value = false;
+      }));
+  XCTAssertTrue(switch_value);
+}
+
+- (void)testLifeCycleNotificationWillEnterForeground {
+  FlutterDartProject* project = [[FlutterDartProject alloc] init];
+  FlutterEngine* engine = [[FlutterEngine alloc] initWithName:@"foobar" project:project];
+  [engine run];
+  NSNotification* sceneNotification =
+      [NSNotification notificationWithName:UISceneWillEnterForegroundNotification
+                                    object:nil
+                                  userInfo:nil];
+  NSNotification* applicationNotification =
+      [NSNotification notificationWithName:UIApplicationWillEnterForegroundNotification
+                                    object:nil
+                                  userInfo:nil];
+  id mockEngine = OCMPartialMock(engine);
+  [[NSNotificationCenter defaultCenter] postNotification:sceneNotification];
+  [[NSNotificationCenter defaultCenter] postNotification:applicationNotification];
+#if APPLICATION_EXTENSION_API_ONLY
+  OCMVerify(times(1), [mockEngine sceneWillEnterForeground:[OCMArg any]]);
+#else
+  OCMVerify(times(1), [mockEngine applicationWillEnterForeground:[OCMArg any]]);
+#endif
+  XCTAssertFalse(engine.isGpuDisabled);
+  bool switch_value = true;
+  [engine shell].GetIsGpuDisabledSyncSwitch()->Execute(
+      fml::SyncSwitch::Handlers().SetIfTrue([&] { switch_value = true; }).SetIfFalse([&] {
+        switch_value = false;
+      }));
+  XCTAssertFalse(switch_value);
+}
+
 @end
diff --git a/shell/platform/darwin/ios/framework/Source/FlutterEngine_Test.h b/shell/platform/darwin/ios/framework/Source/FlutterEngine_Test.h
@@ -35,4 +35,9 @@ class ThreadHost;
 - (void)flutterTextInputView:(FlutterTextInputView*)textInputView
                performAction:(FlutterTextInputAction)action
                   withClient:(int)client;
+- (void)sceneWillEnterForeground:(NSNotification*)notification API_AVAILABLE(ios(13.0));
+- (void)sceneDidEnterBackground:(NSNotification*)notification API_AVAILABLE(ios(13.0));
+- (void)applicationWillEnterForeground:(NSNotification*)notification;
+- (void)applicationDidEnterBackground:(NSNotification*)notification;
+
 @end
diff --git a/shell/platform/darwin/ios/framework/Source/FlutterPlatformPlugin.mm b/shell/platform/darwin/ios/framework/Source/FlutterPlatformPlugin.mm
@@ -269,13 +269,23 @@ - (void)popSystemNavigator:(BOOL)isAnimated {
   // It's also possible in an Add2App scenario that the FlutterViewController was presented
   // outside the context of a UINavigationController, and still wants to be popped.
 
-  UIViewController* engineViewController = [_engine.get() viewController];
+  FlutterViewController* engineViewController = [_engine.get() viewController];
   UINavigationController* navigationController = [engineViewController navigationController];
   if (navigationController) {
     [navigationController popViewControllerAnimated:isAnimated];
   } else {
-    UIViewController* rootViewController =
-        [UIApplication sharedApplication].keyWindow.rootViewController;
+    UIViewController* rootViewController = nil;
+#if APPLICATION_EXTENSION_API_ONLY
+    if (@available(iOS 15.0, *)) {
+      rootViewController =
+          [engineViewController windowSceneIfViewLoaded].keyWindow.rootViewController;
+    } else {
+      FML_LOG(WARNING)
+          << "rootViewController is not available in application extension prior to iOS 15.0.";
+    }
+#else
+    rootViewController = [UIApplication sharedApplication].keyWindow.rootViewController;
+#endif
     if (engineViewController != rootViewController) {
       [engineViewController dismissViewControllerAnimated:isAnimated completion:nil];
     }

diff --git a/shell/platform/darwin/ios/framework/Source/FlutterPlatformPluginTest.mm b/shell/platform/darwin/ios/framework/Source/FlutterPlatformPluginTest.mm
@@ -37,9 +37,8 @@ - (void)testLookUpCallInitiated {
   XCTestExpectation* presentExpectation =
       [self expectationWithDescription:@"Look Up view controller presented"];
 
-  FlutterViewController* engineViewController = [[FlutterViewController alloc] initWithEngine:engine
-                                                                                      nibName:nil
-                                                                                       bundle:nil];
+  FlutterViewController* engineViewController =
+      [[[FlutterViewController alloc] initWithEngine:engine nibName:nil bundle:nil] autorelease];
   FlutterViewController* mockEngineViewController = OCMPartialMock(engineViewController);
 
   FlutterPlatformPlugin* plugin =