Migrate PlatformViewIOS to ARC (flutter/engine#55672)

Migrates PlatformViewIOS from manual reference counting to ARC. Eliminates use of scoped_nsobject, scoped_nsprotocol, and WeakNSObject.

Since this is the last non-ARC file in `flutter_framework_source`, this also eliminates the `flutter_framework_source` target, then also renames the `flutter_framework_source_arc` target to `flutter_framework_source` since... it's ALL ARC.

No semantic changes, therefore no semantic changes to tests.

Issue: https://github.com/flutter/flutter/issues/137801

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

engine/src/flutter/shell/platform/darwin/ios/BUILD.gn

@@ -39,7 +39,7 @@ _flutter_framework_headers = [
 
 _flutter_framework_headers_copy_dir = "$_flutter_framework_dir/Headers"
 
-source_set("flutter_framework_source_arc") {
+source_set("flutter_framework_source") {
   visibility = [ ":*" ]
   cflags_objc = flutter_cflags_objc_arc
   cflags_objcc = flutter_cflags_objcc_arc
@@ -48,15 +48,10 @@ source_set("flutter_framework_source_arc") {
   if (darwin_extension_safe) {
     defines += [ "APPLICATION_EXTENSION_API_ONLY=1" ]
   }
-  allow_circular_includes_from = [ ":flutter_framework_source" ]
+  public_configs = [
-  deps = [
+    ":ios_gpu_configuration_config",
-    ":flutter_framework_source",
+    "//flutter:config",
-    "//flutter/fml",
-    "//flutter/shell/platform/common:common_cpp_input",
-    "//flutter/shell/platform/darwin/common:framework_common",
-    "//flutter/third_party/icu",
   ]
-  public_configs = [ "//flutter:config" ]
 
   sources = [
     "framework/Source/FlutterAppDelegate.mm",
@@ -157,71 +152,18 @@ source_set("flutter_framework_source_arc") {
     "ios_surface_software.mm",
     "platform_message_handler_ios.h",
     "platform_message_handler_ios.mm",
+    "platform_view_ios.h",
+    "platform_view_ios.mm",
     "rendering_api_selection.h",
     "rendering_api_selection.mm",
   ]
-
-  frameworks = [
-    "UIKit.framework",
-    "IOSurface.framework",
-  ]
-
-  deps += [
-    ":ios_gpu_configuration",
-    "//flutter/common:common",
-    "//flutter/common/graphics",
-    "//flutter/lib/ui",
-    "//flutter/runtime",
-    "//flutter/shell/common",
-    "//flutter/shell/platform/darwin/common",
-    "//flutter/shell/platform/darwin/graphics",
-    "//flutter/shell/platform/embedder:embedder_as_internal_library",
-    "//flutter/shell/profiling:profiling",
-    "//flutter/third_party/spring_animation",
-  ]
-}
-
-source_set("flutter_framework_source") {
-  visibility = [ ":*" ]
-  cflags_objc = flutter_cflags_objc
-  cflags_objcc = flutter_cflags_objcc
-
-  deps = []
-
-  sources = [
-    # iOS embedder is migrating to ARC.
-    # New files are highly encouraged to be in ARC.
-    # To add new files in ARC, add them to the `flutter_framework_source_arc` target.
-    "platform_view_ios.h",
-    "platform_view_ios.mm",
-  ]
-
   sources += _flutter_framework_headers
 
-  defines = [ "FLUTTER_FRAMEWORK=1" ]
-  if (darwin_extension_safe) {
-    defines += [ "APPLICATION_EXTENSION_API_ONLY=1" ]
-  }
-
-  deps += [
-    "//flutter/fml",
-    "//flutter/runtime",
-    "//flutter/shell/common",
-    "//flutter/shell/platform/darwin/common",
-    "//flutter/shell/platform/darwin/common:framework_common",
-    "//flutter/shell/platform/embedder:embedder_as_internal_library",
-    "//flutter/shell/profiling:profiling",
-  ]
-
-  public_configs = [
-    ":ios_gpu_configuration_config",
-    "//flutter:config",
-  ]
-
   frameworks = [
     "AudioToolbox.framework",
     "CoreMedia.framework",
     "CoreVideo.framework",
+    "IOSurface.framework",
     "QuartzCore.framework",
     "UIKit.framework",
   ]
@@ -230,6 +172,24 @@ source_set("flutter_framework_source") {
     # Usage in release builds will cause rejection from the App Store.
     frameworks += [ "IOKit.framework" ]
   }
+
+  deps = [
+    ":ios_gpu_configuration",
+    "//flutter/common:common",
+    "//flutter/common/graphics",
+    "//flutter/fml",
+    "//flutter/lib/ui",
+    "//flutter/runtime",
+    "//flutter/shell/common",
+    "//flutter/shell/platform/common:common_cpp_input",
+    "//flutter/shell/platform/darwin/common",
+    "//flutter/shell/platform/darwin/common:framework_common",
+    "//flutter/shell/platform/darwin/graphics",
+    "//flutter/shell/platform/embedder:embedder_as_internal_library",
+    "//flutter/shell/profiling:profiling",
+    "//flutter/third_party/icu",
+    "//flutter/third_party/spring_animation",
+  ]
 }
 
 platform_frameworks_path =
@@ -296,7 +256,6 @@ shared_library("ios_test_flutter") {
   deps = [
     ":flutter_framework",
     ":flutter_framework_source",
-    ":flutter_framework_source_arc",
     ":ios_gpu_configuration",
     "//flutter/common:common",
     "//flutter/lib/ui:ui",
@@ -333,10 +292,7 @@ shared_library("create_flutter_framework_dylib") {
 
   public = _flutter_framework_headers
 
-  deps = [
+  deps = [ ":flutter_framework_source" ]
-    ":flutter_framework_source",
-    ":flutter_framework_source_arc",
-  ]
 
   public_configs = [ "//flutter:config" ]
 }

engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterEngine.mm

@@ -12,7 +12,6 @@
 #include "flutter/common/constants.h"
 #include "flutter/fml/message_loop.h"
 #include "flutter/fml/platform/darwin/platform_version.h"
-#include "flutter/fml/platform/darwin/weak_nsobject.h"
 #include "flutter/fml/trace_event.h"
 #include "flutter/runtime/ptrace_check.h"
 #include "flutter/shell/common/engine.h"
@@ -152,10 +151,6 @@ static constexpr int kNumProfilerSamplesPerSec = 5;
   std::shared_ptr<flutter::ThreadHost> _threadHost;
   std::unique_ptr<flutter::Shell> _shell;
 
-  // TODO(cbracken): https://github.com/flutter/flutter/issues/155943
-  // Migrate to @property(nonatomic, weak).
-  fml::WeakNSObject<FlutterViewController> _viewController;
-
   std::shared_ptr<flutter::PlatformViewsController> _platformViewsController;
   flutter::IOSRenderingAPI _renderingApi;
   std::shared_ptr<flutter::SamplingProfiler> _profiler;
@@ -406,8 +401,7 @@ static constexpr int kNumProfilerSamplesPerSec = 5;
 
 - (void)setViewController:(FlutterViewController*)viewController {
   FML_DCHECK(self.iosPlatformView);
-  _viewController = viewController ? [viewController getWeakNSObject]
+  _viewController = viewController;
-                                   : fml::WeakNSObject<FlutterViewController>();
   self.iosPlatformView->SetOwnerViewController(_viewController);
   [self maybeSetupPlatformViewChannels];
   [self updateDisplays];
@@ -454,7 +448,7 @@ static constexpr int kNumProfilerSamplesPerSec = 5;
     }
   }
   [self.textInputPlugin resetViewResponder];
-  _viewController.reset();
+  _viewController = nil;
 }
 
 - (void)destroyContext {
@@ -466,13 +460,6 @@ static constexpr int kNumProfilerSamplesPerSec = 5;
   _platformViewsController.reset();
 }
 
-- (FlutterViewController*)viewController {
-  if (!_viewController) {
-    return nil;
-  }
-  return _viewController.get();
-}
-
 - (std::shared_ptr<flutter::PlatformViewsController>&)platformViewsController {
   return _platformViewsController;
 }

engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterViewController.mm

@@ -153,11 +153,7 @@ typedef struct MouseState {
 @end
 
 @implementation FlutterViewController {
-  // TODO(cbracken): https://github.com/flutter/flutter/issues/137801
-  // Eliminate once we can use weak pointers in platform_view_ios.h.
-  std::unique_ptr<fml::WeakNSObjectFactory<FlutterViewController>> _weakFactory;
   FlutterEngine* _engine;
-
   flutter::ViewportMetrics _viewportMetrics;
   MouseState _mouseState;
 }
@@ -189,7 +185,6 @@ typedef struct MouseState {
     _flutterView = [[FlutterView alloc] initWithDelegate:_engine
                                                   opaque:self.isViewOpaque
                                          enableWideGamut:engine.project.isWideGamutEnabled];
-    _weakFactory = std::make_unique<fml::WeakNSObjectFactory<FlutterViewController>>(self);
     _ongoingTouches = [[NSMutableSet alloc] init];
 
     // TODO(cbracken): https://github.com/flutter/flutter/issues/157140
@@ -256,7 +251,6 @@ typedef struct MouseState {
     project = [[FlutterDartProject alloc] init];
   }
   FlutterView.forceSoftwareRendering = project.settings.enable_software_rendering;
-  _weakFactory = std::make_unique<fml::WeakNSObjectFactory<FlutterViewController>>(self);
   FlutterEngine* engine = [[FlutterEngine alloc] initWithName:@"io.flutter"
                                                       project:project
                                        allowHeadlessExecution:self.engineAllowHeadlessExecution
@@ -312,10 +306,6 @@ typedef struct MouseState {
   return _engine;
 }
 
-- (fml::WeakNSObject<FlutterViewController>)getWeakNSObject {
-  return _weakFactory->GetWeakNSObject();
-}
-
 - (void)setUpNotificationCenterObservers {
   NSNotificationCenter* center = [NSNotificationCenter defaultCenter];
   [center addObserver:self
@@ -980,10 +970,6 @@ static void SendFakeTouchEvent(UIScreen* screen,
 }
 
 - (void)dealloc {
-  // It will be destroyed and invalidate its weak pointers
-  // before any other members are destroyed.
-  _weakFactory.reset();
-
   // TODO(cbracken): https://github.com/flutter/flutter/issues/157140
   // Eliminate method calls in initializers and dealloc.
   [self removeInternalPlugins];

engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterViewController_Internal.h

@@ -5,7 +5,6 @@
 #ifndef FLUTTER_SHELL_PLATFORM_DARWIN_IOS_FRAMEWORK_SOURCE_FLUTTERVIEWCONTROLLER_INTERNAL_H_
 #define FLUTTER_SHELL_PLATFORM_DARWIN_IOS_FRAMEWORK_SOURCE_FLUTTERVIEWCONTROLLER_INTERNAL_H_
 
-#include "flutter/fml/platform/darwin/weak_nsobject.h"
 #include "flutter/fml/time/time_point.h"
 
 #import "flutter/shell/platform/darwin/ios/framework/Headers/FlutterViewController.h"
@@ -57,7 +56,6 @@ typedef void (^FlutterKeyboardAnimationCallback)(fml::TimePoint);
  */
 @property(nonatomic, assign, readwrite) BOOL prefersStatusBarHidden;
 
-- (fml::WeakNSObject<FlutterViewController>)getWeakNSObject;
 - (std::shared_ptr<flutter::PlatformViewsController>&)platformViewsController;
 - (FlutterRestorationPlugin*)restorationPlugin;
 

engine/src/flutter/shell/platform/darwin/ios/framework/Source/accessibility_bridge.mm

@@ -55,7 +55,7 @@ AccessibilityBridge::AccessibilityBridge(
       weak_factory_(this) {
   accessibility_channel_.reset([[FlutterBasicMessageChannel alloc]
          initWithName:@"flutter/accessibility"
-      binaryMessenger:platform_view->GetOwnerViewController().get().engine.binaryMessenger
+      binaryMessenger:platform_view->GetOwnerViewController().engine.binaryMessenger
                 codec:[FlutterStandardMessageCodec sharedInstance]]);
   [accessibility_channel_.get() setMessageHandler:^(id message, FlutterReply reply) {
     HandleEvent((NSDictionary*)message);
@@ -69,7 +69,7 @@ AccessibilityBridge::~AccessibilityBridge() {
 }
 
 UIView<UITextInput>* AccessibilityBridge::textInputView() {
-  return [[platform_view_->GetOwnerViewController().get().engine textInputPlugin] textInputView];
+  return [[platform_view_->GetOwnerViewController().engine textInputPlugin] textInputView];
 }
 
 void AccessibilityBridge::AccessibilityObjectDidBecomeFocused(int32_t id) {

engine/src/flutter/shell/platform/darwin/ios/framework/Source/accessibility_bridge_test.mm

@@ -1402,9 +1402,7 @@ fml::RefPtr<fml::TaskRunner> CreateNewThread(const std::string& name) {
       /*is_gpu_disabled_sync_switch=*/std::make_shared<fml::SyncSwitch>());
   fml::AutoResetWaitableEvent latch;
   thread_task_runner->PostTask([&] {
-    auto weakFactory =
+    platform_view->SetOwnerViewController(flutterViewController);
-        std::make_unique<fml::WeakNSObjectFactory<FlutterViewController>>(flutterViewController);
-    platform_view->SetOwnerViewController(weakFactory->GetWeakNSObject());
     auto bridge =
         std::make_unique<flutter::AccessibilityBridge>(/*view=*/nil,
                                                        /*platform_view=*/platform_view.get(),
@@ -2091,9 +2089,7 @@ fml::RefPtr<fml::TaskRunner> CreateNewThread(const std::string& name) {
       /*is_gpu_disabled_sync_switch=*/std::make_shared<fml::SyncSwitch>());
   fml::AutoResetWaitableEvent latch;
   thread_task_runner->PostTask([&] {
-    auto weakFactory =
+    platform_view->SetOwnerViewController(flutterViewController);
-        std::make_unique<fml::WeakNSObjectFactory<FlutterViewController>>(flutterViewController);
-    platform_view->SetOwnerViewController(weakFactory->GetWeakNSObject());
     auto bridge =
         std::make_unique<flutter::AccessibilityBridge>(/*view=*/nil,
                                                        /*platform_view=*/platform_view.get(),
@@ -2184,9 +2180,7 @@ fml::RefPtr<fml::TaskRunner> CreateNewThread(const std::string& name) {
 
     OCMStub([mockFlutterViewController platformViewsController])
         .andReturn(flutterPlatformViewsController.get());
-    auto weakFactory = std::make_unique<fml::WeakNSObjectFactory<FlutterViewController>>(
+    platform_view->SetOwnerViewController(mockFlutterViewController);
-        mockFlutterViewController);
-    platform_view->SetOwnerViewController(weakFactory->GetWeakNSObject());
 
     platform_view->SetSemanticsEnabled(true);
     XCTAssertNotEqual(test_delegate.set_semantics_enabled_calls, 0);

engine/src/flutter/shell/platform/darwin/ios/platform_view_ios.h

@@ -9,8 +9,6 @@
 
 #include "flutter/fml/closure.h"
 #include "flutter/fml/macros.h"
-#include "flutter/fml/platform/darwin/scoped_nsobject.h"
-#include "flutter/fml/platform/darwin/weak_nsobject.h"
 #include "flutter/shell/common/platform_view.h"
 #import "flutter/shell/platform/darwin/common/framework/Headers/FlutterTexture.h"
 #import "flutter/shell/platform/darwin/ios/framework/Headers/FlutterViewController.h"
@@ -59,14 +57,14 @@ class PlatformViewIOS final : public PlatformView {
    * Returns the `FlutterViewController` currently attached to the `FlutterEngine` owning
    * this PlatformViewIOS.
    */
-  fml::WeakNSObject<FlutterViewController> GetOwnerViewController() const;
+  FlutterViewController* GetOwnerViewController() const __attribute__((cf_audited_transfer));
 
   /**
    * Updates the `FlutterViewController` currently attached to the `FlutterEngine` owning
    * this PlatformViewIOS. This should be updated when the `FlutterEngine`
    * is given a new `FlutterViewController`.
    */
-  void SetOwnerViewController(const fml::WeakNSObject<FlutterViewController>& owner_controller);
+  void SetOwnerViewController(__weak FlutterViewController* owner_controller);
 
   /**
    * Called one time per `FlutterViewController` when the `FlutterViewController`'s
@@ -133,7 +131,7 @@ class PlatformViewIOS final : public PlatformView {
     std::function<void(bool)> set_semantics_enabled_;
   };
 
-  fml::WeakNSObject<FlutterViewController> owner_controller_;
+  __weak FlutterViewController* owner_controller_;
   // Since the `ios_surface_` is created on the platform thread but
   // used on the raster thread we need to protect it with a mutex.
   std::mutex ios_surface_mutex_;
@@ -141,7 +139,6 @@ class PlatformViewIOS final : public PlatformView {
   std::shared_ptr<IOSContext> ios_context_;
   const std::shared_ptr<PlatformViewsController>& platform_views_controller_;
   AccessibilityBridgeManager accessibility_bridge_;
-  fml::scoped_nsprotocol<FlutterTextInputPlugin*> text_input_plugin_;
   ScopedObserver dealloc_view_controller_observer_;
   std::vector<std::string> platform_resolved_locale_;
   std::shared_ptr<PlatformMessageHandlerIos> platform_message_handler_;

engine/src/flutter/shell/platform/darwin/ios/platform_view_ios.mm

@@ -14,6 +14,8 @@
 #import "flutter/shell/platform/darwin/ios/framework/Source/FlutterViewController_Internal.h"
 #import "flutter/shell/platform/darwin/ios/framework/Source/vsync_waiter_ios.h"
 
+FLUTTER_ASSERT_ARC
+
 namespace flutter {
 
 PlatformViewIOS::AccessibilityBridgeManager::AccessibilityBridgeManager(
@@ -74,12 +76,11 @@ void PlatformViewIOS::HandlePlatformMessage(std::unique_ptr<flutter::PlatformMes
   platform_message_handler_->HandlePlatformMessage(std::move(message));
 }
 
-fml::WeakNSObject<FlutterViewController> PlatformViewIOS::GetOwnerViewController() const {
+FlutterViewController* PlatformViewIOS::GetOwnerViewController() const {
   return owner_controller_;
 }
 
-void PlatformViewIOS::SetOwnerViewController(
+void PlatformViewIOS::SetOwnerViewController(__weak FlutterViewController* owner_controller) {
-    const fml::WeakNSObject<FlutterViewController>& owner_controller) {
   FML_DCHECK(task_runners_.GetPlatformTaskRunner()->RunsTasksOnCurrentThread());
   std::lock_guard<std::mutex> guard(ios_surface_mutex_);
   if (ios_surface_ || !owner_controller) {
@@ -91,17 +92,17 @@ void PlatformViewIOS::SetOwnerViewController(
 
   // Add an observer that will clear out the owner_controller_ ivar and
   // the accessibility_bridge_ in case the view controller is deleted.
-  dealloc_view_controller_observer_.reset(
+  dealloc_view_controller_observer_.reset([[NSNotificationCenter defaultCenter]
-      [[[NSNotificationCenter defaultCenter] addObserverForName:FlutterViewControllerWillDealloc
+      addObserverForName:FlutterViewControllerWillDealloc
-                                                         object:owner_controller_.get()
+                  object:owner_controller_
                    queue:[NSOperationQueue mainQueue]
               usingBlock:^(NSNotification* note) {
                 // Implicit copy of 'this' is fine.
                 accessibility_bridge_.Clear();
-                                                       owner_controller_.reset();
+                owner_controller_ = nil;
-                                                     }] retain]);
+              }]);
 
-  if (owner_controller_ && [owner_controller_.get() isViewLoaded]) {
+  if (owner_controller_ && owner_controller_.isViewLoaded) {
     this->attachView();
   }
   // Do not call `NotifyCreated()` here - let FlutterViewController take care
@@ -112,17 +113,16 @@ void PlatformViewIOS::SetOwnerViewController(
 
 void PlatformViewIOS::attachView() {
   FML_DCHECK(owner_controller_);
-  FML_DCHECK(owner_controller_.get().isViewLoaded)
+  FML_DCHECK(owner_controller_.isViewLoaded) << "FlutterViewController's view should be loaded "
-      << "FlutterViewController's view should be loaded "
                                                 "before attaching to PlatformViewIOS.";
-  auto flutter_view = static_cast<FlutterView*>(owner_controller_.get().view);
+  FlutterView* flutter_view = static_cast<FlutterView*>(owner_controller_.view);
-  auto ca_layer = fml::scoped_nsobject<CALayer>{[[flutter_view layer] retain]};
+  auto ca_layer = fml::scoped_nsobject<CALayer>{[flutter_view layer]};
   ios_surface_ = IOSSurface::Create(ios_context_, ca_layer);
   FML_DCHECK(ios_surface_ != nullptr);
 
   if (accessibility_bridge_) {
     accessibility_bridge_.Set(std::make_unique<AccessibilityBridge>(
-        owner_controller_.get(), this, [owner_controller_.get() platformViewsController]));
+        owner_controller_, this, owner_controller_.platformViewsController));
   }
 }
 
@@ -135,7 +135,7 @@ PointerDataDispatcherMaker PlatformViewIOS::GetDispatcherMaker() {
 void PlatformViewIOS::RegisterExternalTexture(int64_t texture_id,
                                               NSObject<FlutterTexture>* texture) {
   RegisterTexture(ios_context_->CreateExternalTexture(
-      texture_id, fml::scoped_nsobject<NSObject<FlutterTexture>>{[texture retain]}));
+      texture_id, fml::scoped_nsobject<NSObject<FlutterTexture>>{texture}));
 }
 
 // |PlatformView|
@@ -174,7 +174,7 @@ void PlatformViewIOS::SetSemanticsEnabled(bool enabled) {
   }
   if (enabled && !accessibility_bridge_) {
     accessibility_bridge_.Set(std::make_unique<AccessibilityBridge>(
-        owner_controller_.get(), this, [owner_controller_.get() platformViewsController]));
+        owner_controller_, this, owner_controller_.platformViewsController));
   } else if (!enabled && accessibility_bridge_) {
     accessibility_bridge_.Clear();
   } else {
@@ -194,7 +194,7 @@ void PlatformViewIOS::UpdateSemantics(flutter::SemanticsNodeUpdates update,
   if (accessibility_bridge_) {
     accessibility_bridge_.get()->UpdateSemantics(std::move(update), actions);
     [[NSNotificationCenter defaultCenter] postNotificationName:FlutterSemanticsUpdateNotification
-                                                        object:owner_controller_.get()];
+                                                        object:owner_controller_];
   }
 }
 
@@ -210,8 +210,8 @@ void PlatformViewIOS::OnPreEngineRestart() const {
   if (!owner_controller_) {
     return;
   }
-  [owner_controller_.get() platformViewsController]->Reset();
+  owner_controller_.platformViewsController->Reset();
-  [[owner_controller_.get() restorationPlugin] reset];
+  [owner_controller_.restorationPlugin reset];
 }
 
 std::unique_ptr<std::vector<std::string>> PlatformViewIOS::ComputePlatformResolvedLocales(
@@ -253,7 +253,6 @@ PlatformViewIOS::ScopedObserver::ScopedObserver() {}
 PlatformViewIOS::ScopedObserver::~ScopedObserver() {
   if (observer_) {
     [[NSNotificationCenter defaultCenter] removeObserver:observer_];
-    [observer_ release];
   }
 }
 
@@ -261,7 +260,6 @@ void PlatformViewIOS::ScopedObserver::reset(id<NSObject> observer) {
   if (observer != observer_) {
     if (observer_) {
       [[NSNotificationCenter defaultCenter] removeObserver:observer_];
-      [observer_ release];
     }
     observer_ = observer;
   }