Migrate FlutterCallbackCache and FlutterKeyboardManager to ARC (#51983)

Smart pointers support ARC as of #47612, and the unit tests were migrated in #48162.

Migrate`FlutterCallbackCache` and `FlutterKeyboardManager` from MRC to ARC.  These files do not themselves import any MRC files, making them leaf nodes in the dependency graph of MRC files.  

Doing a few at a time to make the dependency graph manageable, and to easily revert if this causes retain cycles or other memory management issues.

Part of flutter/flutter#137801.

shell/platform/darwin/common/framework/Source/FlutterChannelsTest.m

@@ -168,7 +168,7 @@ - (void)testResize {
   [binaryMessenger stopMocking];
 }
 
-- (bool)testSetWarnsOnOverflow {
+- (void)testSetWarnsOnOverflow {
   NSString* channelName = @"flutter/test";
   id binaryMessenger = OCMStrictProtocolMock(@protocol(FlutterBinaryMessenger));
   id codec = OCMProtocolMock(@protocol(FlutterMethodCodec));

shell/platform/darwin/ios/BUILD.gn

@@ -59,10 +59,14 @@ source_set("flutter_framework_source_arc") {
   public_configs = [ "//flutter:config" ]
 
   sources = [
+    "framework/Source/FlutterCallbackCache.mm",
+    "framework/Source/FlutterCallbackCache_Internal.h",
     "framework/Source/FlutterEmbedderKeyResponder.h",
     "framework/Source/FlutterEmbedderKeyResponder.mm",
     "framework/Source/FlutterKeyPrimaryResponder.h",
     "framework/Source/FlutterKeySecondaryResponder.h",
+    "framework/Source/FlutterKeyboardManager.h",
+    "framework/Source/FlutterKeyboardManager.mm",
     "framework/Source/FlutterMetalLayer.h",
     "framework/Source/FlutterMetalLayer.mm",
     "framework/Source/FlutterRestorationPlugin.h",
@@ -83,7 +87,10 @@ source_set("flutter_framework_source_arc") {
     "IOSurface.framework",
   ]
 
-  deps += [ "//flutter/shell/platform/embedder:embedder_as_internal_library" ]
+  deps += [
+    "//flutter/lib/ui",
+    "//flutter/shell/platform/embedder:embedder_as_internal_library",
+  ]
 }
 
 source_set("flutter_framework_source") {
@@ -98,8 +105,6 @@ source_set("flutter_framework_source") {
     # New files are highly encouraged to be in ARC.
     # To add new files in ARC, add them to the `flutter_framework_source_arc` target.
     "framework/Source/FlutterAppDelegate.mm",
-    "framework/Source/FlutterCallbackCache.mm",
-    "framework/Source/FlutterCallbackCache_Internal.h",
     "framework/Source/FlutterChannelKeyResponder.h",
     "framework/Source/FlutterChannelKeyResponder.mm",
     "framework/Source/FlutterDartProject.mm",
@@ -110,8 +115,6 @@ source_set("flutter_framework_source") {
     "framework/Source/FlutterEngineGroup.mm",
     "framework/Source/FlutterEngine_Internal.h",
     "framework/Source/FlutterHeadlessDartRunner.mm",
-    "framework/Source/FlutterKeyboardManager.h",
-    "framework/Source/FlutterKeyboardManager.mm",
     "framework/Source/FlutterOverlayView.h",
     "framework/Source/FlutterOverlayView.mm",
     "framework/Source/FlutterPlatformPlugin.h",

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

@@ -7,15 +7,9 @@
 #include "flutter/fml/logging.h"
 #include "flutter/lib/ui/plugins/callback_cache.h"
 
-@implementation FlutterCallbackInformation
-
-- (void)dealloc {
-  [_callbackName release];
-  [_callbackClassName release];
-  [_callbackLibraryPath release];
-  [super dealloc];
-}
+FLUTTER_ASSERT_ARC
 
+@implementation FlutterCallbackInformation
 @end
 
 @implementation FlutterCallbackCache
@@ -25,7 +19,7 @@ + (FlutterCallbackInformation*)lookupCallbackInformation:(int64_t)handle {
   if (info == nullptr) {
     return nil;
   }
-  FlutterCallbackInformation* new_info = [[[FlutterCallbackInformation alloc] init] autorelease];
+  FlutterCallbackInformation* new_info = [[FlutterCallbackInformation alloc] init];
   new_info.callbackName = [NSString stringWithUTF8String:info->name.c_str()];
   new_info.callbackClassName = [NSString stringWithUTF8String:info->class_name.c_str()];
   new_info.callbackLibraryPath = [NSString stringWithUTF8String:info->library_path.c_str()];

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

@@ -3,8 +3,11 @@
 // found in the LICENSE file.
 
 #import "flutter/shell/platform/darwin/ios/framework/Source/FlutterKeyboardManager.h"
+
 #include "flutter/fml/platform/darwin/message_loop_darwin.h"
-#include "flutter/fml/platform/darwin/weak_nsobject.h"
+#import "flutter/shell/platform/darwin/common/framework/Headers/FlutterMacros.h"
+
+FLUTTER_ASSERT_ARC
 
 static constexpr CFTimeInterval kDistantFuture = 1.0e10;
 
@@ -13,13 +16,13 @@ @interface FlutterKeyboardManager ()
 /**
  * The primary responders added by addPrimaryResponder.
  */
-@property(nonatomic, retain, readonly)
+@property(nonatomic, copy, readonly)
     NSMutableArray<id<FlutterKeyPrimaryResponder>>* primaryResponders;
 
 /**
  * The secondary responders added by addSecondaryResponder.
  */
-@property(nonatomic, retain, readonly)
+@property(nonatomic, copy, readonly)
     NSMutableArray<id<FlutterKeySecondaryResponder>>* secondaryResponders;
 
 - (void)dispatchToSecondaryResponders:(nonnull FlutterUIPressProxy*)press
@@ -28,16 +31,13 @@ - (void)dispatchToSecondaryResponders:(nonnull FlutterUIPressProxy*)press
 
 @end
 
-@implementation FlutterKeyboardManager {
-  std::unique_ptr<fml::WeakNSObjectFactory<FlutterKeyboardManager>> _weakFactory;
-}
+@implementation FlutterKeyboardManager
 
 - (nonnull instancetype)init {
   self = [super init];
   if (self != nil) {
     _primaryResponders = [[NSMutableArray alloc] init];
     _secondaryResponders = [[NSMutableArray alloc] init];
-    _weakFactory = std::make_unique<fml::WeakNSObjectFactory<FlutterKeyboardManager>>(self);
   }
   return self;
 }
@@ -50,24 +50,6 @@ - (void)addSecondaryResponder:(nonnull id<FlutterKeySecondaryResponder>)responde
   [_secondaryResponders addObject:responder];
 }
 
-- (void)dealloc {
-  // It will be destroyed and invalidate its weak pointers
-  // before any other members are destroyed.
-  _weakFactory.reset();
-
-  [_primaryResponders removeAllObjects];
-  [_secondaryResponders removeAllObjects];
-  [_primaryResponders release];
-  [_secondaryResponders release];
-  _primaryResponders = nil;
-  _secondaryResponders = nil;
-  [super dealloc];
-}
-
-- (fml::WeakNSObject<FlutterKeyboardManager>)getWeakNSObject {
-  return _weakFactory->GetWeakNSObject();
-}
-
 - (void)handlePress:(nonnull FlutterUIPressProxy*)press
          nextAction:(nonnull void (^)())next API_AVAILABLE(ios(13.4)) {
   if (@available(iOS 13.4, *)) {
@@ -89,7 +71,7 @@ - (void)handlePress:(nonnull FlutterUIPressProxy*)press
       // encounter.
       NSAssert([_primaryResponders count] >= 0, @"At least one primary responder must be added.");
 
-      __block auto weakSelf = [self getWeakNSObject];
+      __block __weak __typeof(self) weakSelf = self;
       __block NSUInteger unreplied = [self.primaryResponders count];
       __block BOOL anyHandled = false;
       FlutterAsyncKeyCallback replyCallback = ^(BOOL handled) {
@@ -98,7 +80,7 @@ - (void)handlePress:(nonnull FlutterUIPressProxy*)press
         anyHandled = anyHandled || handled;
         if (unreplied == 0) {
           if (!anyHandled && weakSelf) {
-            [weakSelf.get() dispatchToSecondaryResponders:press complete:completeCallback];
+            [weakSelf dispatchToSecondaryResponders:press complete:completeCallback];
           } else {
             completeCallback(true, press);
           }

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

@@ -23,43 +23,6 @@
 
 using namespace flutter::testing;
 
-/// Sometimes we have to use a custom mock to avoid retain cycles in ocmock.
-@interface FlutterEnginePartialMock : FlutterEngine
-@property(nonatomic, strong) FlutterBasicMessageChannel* lifecycleChannel;
-@property(nonatomic, weak) FlutterViewController* viewController;
-@property(nonatomic, assign) BOOL didCallNotifyLowMemory;
-@end
-
-@interface FlutterEngine ()
-- (BOOL)createShell:(NSString*)entrypoint
-         libraryURI:(NSString*)libraryURI
-       initialRoute:(NSString*)initialRoute;
-- (void)dispatchPointerDataPacket:(std::unique_ptr<flutter::PointerDataPacket>)packet;
-@end
-
-@interface FlutterEngine (TestLowMemory)
-- (void)notifyLowMemory;
-@end
-
-extern NSNotificationName const FlutterViewControllerWillDealloc;
-
-/// A simple mock class for FlutterEngine.
-///
-/// OCMockClass can't be used for FlutterEngine sometimes because OCMock retains arguments to
-/// invocations and since the init for FlutterViewController calls a method on the
-/// FlutterEngine it creates a retain cycle that stops us from testing behaviors related to
-/// deleting FlutterViewControllers.
-@interface MockEngine : NSObject
-@end
-
-@interface FlutterKeyboardManagerUnittestsObjC : NSObject
-- (bool)nextResponderShouldThrowOnPressesEnded;
-- (bool)singlePrimaryResponder;
-- (bool)doublePrimaryResponder;
-- (bool)singleSecondaryResponder;
-- (bool)emptyNextResponder;
-@end
-
 namespace {
 
 typedef void (^KeyCallbackSetter)(FlutterUIPressProxy* press, FlutterAsyncKeyCallback callback)
@@ -68,52 +31,28 @@ typedef void (^KeyCallbackSetter)(FlutterUIPressProxy* press, FlutterAsyncKeyCal
 
 }  // namespace
 
+// These tests were designed to run on iOS 13.4 or later.
+API_AVAILABLE(ios(13.4))
 @interface FlutterKeyboardManagerTest : XCTestCase
-@property(nonatomic, strong) id mockEngine;
-- (FlutterViewController*)mockOwnerWithPressesBeginOnlyNext API_AVAILABLE(ios(13.4));
 @end
 
 @implementation FlutterKeyboardManagerTest
 
-- (void)setUp {
-  // All of these tests were designed to run on iOS 13.4 or later.
-  if (@available(iOS 13.4, *)) {
-  } else {
-    XCTSkip(@"Required API not present for test.");
-  }
-
-  [super setUp];
-  self.mockEngine = OCMClassMock([FlutterEngine class]);
-}
-
-- (void)tearDown {
-  // We stop mocking here to avoid retain cycles that stop
-  // FlutterViewControllers from deallocing.
-  [self.mockEngine stopMocking];
-  self.mockEngine = nil;
-  [super tearDown];
-}
-
-- (id)checkKeyDownEvent:(UIKeyboardHIDUsage)keyCode API_AVAILABLE(ios(13.4)) {
-  return [OCMArg checkWithBlock:^BOOL(id value) {
-    if (![value isKindOfClass:[FlutterUIPressProxy class]]) {
-      return NO;
-    }
-    FlutterUIPressProxy* press = value;
-    return press.key.keyCode == keyCode;
-  }];
-}
-
-- (id<FlutterKeyPrimaryResponder>)mockPrimaryResponder:(KeyCallbackSetter)callbackSetter
-    API_AVAILABLE(ios(13.4)) {
+- (id<FlutterKeyPrimaryResponder>)mockPrimaryResponder:(KeyCallbackSetter)callbackSetter {
   id<FlutterKeyPrimaryResponder> mock =
       OCMStrictProtocolMock(@protocol(FlutterKeyPrimaryResponder));
   OCMStub([mock handlePress:[OCMArg any] callback:[OCMArg any]])
       .andDo((^(NSInvocation* invocation) {
-        FlutterUIPressProxy* press;
-        FlutterAsyncKeyCallback callback;
-        [invocation getArgument:&press atIndex:2];
-        [invocation getArgument:&callback atIndex:3];
+        __unsafe_unretained FlutterUIPressProxy* pressUnsafe;
+        __unsafe_unretained FlutterAsyncKeyCallback callbackUnsafe;
+
+        [invocation getArgument:&pressUnsafe atIndex:2];
+        [invocation getArgument:&callbackUnsafe atIndex:3];
+
+        // Retain the unretained parameters so they can
+        // be run in the perform block when this invocation goes out of scope.
+        FlutterUIPressProxy* press = pressUnsafe;
+        FlutterAsyncKeyCallback callback = callbackUnsafe;
         CFRunLoopPerformBlock(CFRunLoopGetCurrent(),
                               fml::MessageLoopDarwin::kMessageLoopCFRunLoopMode, ^() {
                                 callbackSetter(press, callback);
@@ -122,8 +61,7 @@ - (id)checkKeyDownEvent:(UIKeyboardHIDUsage)keyCode API_AVAILABLE(ios(13.4)) {
   return mock;
 }
 
-- (id<FlutterKeySecondaryResponder>)mockSecondaryResponder:(BoolGetter)resultGetter
-    API_AVAILABLE(ios(13.4)) {
+- (id<FlutterKeySecondaryResponder>)mockSecondaryResponder:(BoolGetter)resultGetter {
   id<FlutterKeySecondaryResponder> mock =
       OCMStrictProtocolMock(@protocol(FlutterKeySecondaryResponder));
   OCMStub([mock handlePress:[OCMArg any]]).andDo((^(NSInvocation* invocation) {
@@ -133,32 +71,27 @@ - (id)checkKeyDownEvent:(UIKeyboardHIDUsage)keyCode API_AVAILABLE(ios(13.4)) {
   return mock;
 }
 
-- (FlutterViewController*)mockOwnerWithPressesBeginOnlyNext API_AVAILABLE(ios(13.4)) {
+- (void)testNextResponderShouldThrowOnPressesEnded {
   // The nextResponder is a strict mock and hasn't stubbed pressesEnded.
   // An error will be thrown on pressesEnded.
   UIResponder* nextResponder = OCMStrictClassMock([UIResponder class]);
-  OCMStub([nextResponder pressesBegan:[OCMArg any] withEvent:[OCMArg any]]).andDo(nil);
+  OCMStub([nextResponder pressesBegan:OCMOCK_ANY withEvent:OCMOCK_ANY]);
 
-  FlutterViewController* viewController =
-      [[FlutterViewController alloc] initWithEngine:self.mockEngine nibName:nil bundle:nil];
+  id mockEngine = OCMClassMock([FlutterEngine class]);
+  FlutterViewController* viewController = [[FlutterViewController alloc] initWithEngine:mockEngine
+                                                                                nibName:nil
+                                                                                 bundle:nil];
   FlutterViewController* owner = OCMPartialMock(viewController);
   OCMStub([owner nextResponder]).andReturn(nextResponder);
-  return owner;
-}
 
-// Verify that the nextResponder returned from mockOwnerWithPressesBeginOnlyNext()
-// throws exception when pressesEnded is called.
-- (bool)testNextResponderShouldThrowOnPressesEnded API_AVAILABLE(ios(13.4)) {
-  FlutterViewController* owner = [self mockOwnerWithPressesBeginOnlyNext];
-  @try {
-    [owner.nextResponder pressesEnded:[NSSet init] withEvent:[[UIPressesEvent alloc] init]];
-    return false;
-  } @catch (...) {
-    return true;
-  }
+  XCTAssertThrowsSpecificNamed([owner.nextResponder pressesEnded:[[NSSet alloc] init]
+                                                       withEvent:[[UIPressesEvent alloc] init]],
+                               NSException, NSInternalInconsistencyException);
+
+  [mockEngine stopMocking];
 }
 
-- (void)testSinglePrimaryResponder API_AVAILABLE(ios(13.4)) {
+- (void)testSinglePrimaryResponder {
   FlutterKeyboardManager* manager = [[FlutterKeyboardManager alloc] init];
   __block BOOL primaryResponse = FALSE;
   __block int callbackCount = 0;
@@ -190,7 +123,7 @@ - (void)testSinglePrimaryResponder API_AVAILABLE(ios(13.4)) {
   XCTAssertFalse(completeHandled);
 }
 
-- (void)testDoublePrimaryResponder API_AVAILABLE(ios(13.4)) {
+- (void)testDoublePrimaryResponder {
   FlutterKeyboardManager* manager = [[FlutterKeyboardManager alloc] init];
 
   __block BOOL callback1Response = FALSE;
@@ -253,7 +186,7 @@ - (void)testDoublePrimaryResponder API_AVAILABLE(ios(13.4)) {
   XCTAssertFalse(somethingWasHandled);
 }
 
-- (void)testSingleSecondaryResponder API_AVAILABLE(ios(13.4)) {
+- (void)testSingleSecondaryResponder {
   FlutterKeyboardManager* manager = [[FlutterKeyboardManager alloc] init];
 
   __block BOOL primaryResponse = FALSE;
@@ -308,7 +241,7 @@ - (void)testSingleSecondaryResponder API_AVAILABLE(ios(13.4)) {
   XCTAssertFalse(completeHandled);
 }
 
-- (void)testEventsProcessedSequentially API_AVAILABLE(ios(13.4)) {
+- (void)testEventsProcessedSequentially {
   constexpr UIKeyboardHIDUsage keyId1 = (UIKeyboardHIDUsage)0x50;
   constexpr UIKeyboardHIDUsage keyId2 = (UIKeyboardHIDUsage)0x51;
   FlutterUIPressProxy* event1 = keyDownEvent(keyId1);