ios: Add option to use RN's "New Architecture"

The bulk of this code only does anything if we enable New Arch.
I'm not sure if some of the other bits might have some behavioral
effect, though.

This squashes together the following template changes upstream on the
way to RN v0.68:

facebook/react-native@73a04d145 Refactor the iOS app template to move setups to a helper class
facebook/react-native@8ec0e6919 Add turbo module support in the default app template
facebook/react-native@2e9a376c8 Add fabric option to the default app template.
facebook/react-native@c0c543995 Rename the new architecture flag to RCT_NEW_ARCH_ENABLED
facebook/react-native@1cd8f05ee Refactor app template setup util functions
facebook/react-native@6a046fb9f Fix build issue for the new app template
facebook/react-native@e330eee9c Add Other C++ flags when RCT_NEW_ARCH_ENABLE=1
facebook/react-native@ccd170809 … Consider relative to pwd installation root …

They use new APIs introduced to RN at the same time, some of which get
refactored further by the later commits; the last one fixes a bug a
previous one introduced in the Podfile.

It also includes:

* Fixing the type of `rootView` back to the more specific `RCTRootView *`,
  rather than `UIView *`.  We need the more specific type when setting
  its `.loadingView` property below.

* Re-following Expo instructions for adding Expo to an existing RN app:
    https://docs.expo.dev/bare/installing-expo-modules/#configuration-for-ios
  This just requires the one hunk of that diff that changes the
  initializer for `rootView`.

Author: gnprice

ios/Podfile

@@ -9,10 +9,16 @@ require_relative '../node_modules/@react-native-community/cli-platform-ios/nativ
 target 'ZulipMobile' do
   config = use_native_modules!
 
+  # Flags change depending on the env values.
+  flags = get_default_flags()
+
   use_react_native!(
     :path => config[:reactNativePath],
     # to enable hermes on iOS, change `false` to `true` and then install pods
-    :hermes_enabled => false
+    :hermes_enabled => flags[:hermes_enabled],
+    :fabric_enabled => flags[:fabric_enabled],
+    # An absolute path to your application root.
+    :app_path => "#{Pod::Config.instance.installation_root}/.."
   )
 
   # Enables Flipper.

ios/Podfile.lock

@@ -757,6 +757,6 @@ SPEC CHECKSUMS:
   Yoga: c4d61225a466f250c35c1ee78d2d0b3d41fe661c
   YogaKit: f782866e155069a2cca2517aafea43200b01fd5a
 
-PODFILE CHECKSUM: 5246a27326b34ca5020f4cfdd2d084a266874427
+PODFILE CHECKSUM: 1576cc1dcc2b42d6d0484ee84b568d44a1a91346
 
 COCOAPODS: 1.11.3

ios/ZulipMobile.xcodeproj/project.pbxproj

@@ -460,7 +460,7 @@
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
 				CLANG_ANALYZER_LOCALIZABILITY_NONLOCALIZED = YES;
-				CLANG_CXX_LANGUAGE_STANDARD = "gnu++0x";
+				CLANG_CXX_LANGUAGE_STANDARD = "c++17";
 				CLANG_CXX_LIBRARY = "libc++";
 				CLANG_ENABLE_MODULES = YES;
 				CLANG_ENABLE_OBJC_ARC = YES;
@@ -512,6 +512,12 @@
 				);
 				MTL_ENABLE_DEBUG_INFO = YES;
 				ONLY_ACTIVE_ARCH = YES;
+				OTHER_CPLUSPLUSFLAGS = (
+					"$(OTHER_CFLAGS)",
+					"-DFOLLY_NO_CONFIG",
+					"-DFOLLY_MOBILE=1",
+					"-DFOLLY_USE_LIBCPP=1",
+				);
 				PRODUCT_BUNDLE_IDENTIFIER = org.zulip.ZulipMobile;
 				SDKROOT = iphoneos;
 			};
@@ -522,7 +528,7 @@
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
 				CLANG_ANALYZER_LOCALIZABILITY_NONLOCALIZED = YES;
-				CLANG_CXX_LANGUAGE_STANDARD = "gnu++0x";
+				CLANG_CXX_LANGUAGE_STANDARD = "c++17";
 				CLANG_CXX_LIBRARY = "libc++";
 				CLANG_ENABLE_MODULES = YES;
 				CLANG_ENABLE_OBJC_ARC = YES;
@@ -566,6 +572,12 @@
 					"$(inherited)",
 				);
 				MTL_ENABLE_DEBUG_INFO = NO;
+				OTHER_CPLUSPLUSFLAGS = (
+					"$(OTHER_CFLAGS)",
+					"-DFOLLY_NO_CONFIG",
+					"-DFOLLY_MOBILE=1",
+					"-DFOLLY_USE_LIBCPP=1",
+				);
 				PRODUCT_BUNDLE_IDENTIFIER = org.zulip.ZulipMobile;
 				SDKROOT = iphoneos;
 				VALIDATE_PRODUCT = YES;

ios/ZulipMobile/AppDelegate.mm

@@ -9,39 +9,46 @@
 #import <UserNotifications/UserNotifications.h>
 #import <RNCPushNotificationIOS.h>
 
-#ifdef FB_SONARKIT_ENABLED
-  #import <FlipperKit/FlipperClient.h>
-  #import <FlipperKitLayoutPlugin/FlipperKitLayoutPlugin.h>
-  #import <FlipperKitUserDefaultsPlugin/FKUserDefaultsPlugin.h>
-  #import <FlipperKitNetworkPlugin/FlipperKitNetworkPlugin.h>
-  #import <SKIOSNetworkPlugin/SKIOSNetworkAdapter.h>
-  #import <FlipperKitReactPlugin/FlipperKitReactPlugin.h>
-
-  static void InitializeFlipper(UIApplication *application) {
-    FlipperClient *client = [FlipperClient sharedClient];
-    SKDescriptorMapper *layoutDescriptorMapper = [[SKDescriptorMapper alloc] initWithDefaults];
-    [client addPlugin:[[FlipperKitLayoutPlugin alloc] initWithRootNode:application withDescriptorMapper:layoutDescriptorMapper]];
-    [client addPlugin:[[FKUserDefaultsPlugin alloc] initWithSuiteName:nil]];
-    [client addPlugin:[FlipperKitReactPlugin new]];
-    [client addPlugin:[[FlipperKitNetworkPlugin alloc] initWithNetworkAdapter:[SKIOSNetworkAdapter new]]];
-    [client start];
-  }
+#import <React/RCTAppSetupUtils.h>
+
+#if RCT_NEW_ARCH_ENABLED
+#import <React/CoreModulesPlugins.h>
+#import <React/RCTCxxBridgeDelegate.h>
+#import <ReactCommon/RCTTurboModuleManager.h>
+#import <React/RCTFabricSurfaceHostingProxyRootView.h>
+#import <React/RCTSurfacePresenter.h>
+#import <React/RCTSurfacePresenterBridgeAdapter.h>
+
+#import <react/config/ReactNativeConfig.h>
+
+@interface AppDelegate () <RCTCxxBridgeDelegate, RCTTurboModuleManagerDelegate> {
+  RCTTurboModuleManager *_turboModuleManager;
+  RCTSurfacePresenterBridgeAdapter *_bridgeAdapter;
+  std::shared_ptr<const facebook::react::ReactNativeConfig> _reactNativeConfig;
+  facebook::react::ContextContainer::Shared _contextContainer;
+}
+@end
 #endif
 
 @implementation AppDelegate
 
 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
 {
-  #ifdef FB_SONARKIT_ENABLED
-    InitializeFlipper(application);
-  #endif
+  RCTAppSetupPrepareApp(application);
 
   RCTSetLogThreshold(RCTLogLevelError);
 
   RCTBridge *bridge = [self.reactDelegate createBridgeWithDelegate:self launchOptions:launchOptions];
-  RCTRootView *rootView = [self.reactDelegate createRootViewWithBridge:bridge
-                                                      moduleName:@"ZulipMobile"
-                                               initialProperties:nil];
+
+#if RCT_NEW_ARCH_ENABLED
+  _contextContainer = std::make_shared<facebook::react::ContextContainer const>();
+  _reactNativeConfig = std::make_shared<facebook::react::EmptyReactNativeConfig const>();
+  _contextContainer->insert("ReactNativeConfig", _reactNativeConfig);
+  _bridgeAdapter = [[RCTSurfacePresenterBridgeAdapter alloc] initWithBridge:bridge contextContainer:_contextContainer];
+  bridge.surfacePresenter = _bridgeAdapter.surfacePresenter;
+#endif
+
+  RCTRootView *rootView = [self.reactDelegate createRootViewWithBridge:bridge moduleName:@"ZulipMobile" initialProperties:nil];
 
   UIView* loadingView = [[UIView alloc] initWithFrame:[UIScreen mainScreen].bounds];
   loadingView.backgroundColor = [UIColor colorNamed:@"Brand"];
@@ -140,4 +147,42 @@ -(void)userNotificationCenter:(UNUserNotificationCenter *)center
  );
 }
 
+#if RCT_NEW_ARCH_ENABLED
+
+#pragma mark - RCTCxxBridgeDelegate
+
+- (std::unique_ptr<facebook::react::JSExecutorFactory>)jsExecutorFactoryForBridge:(RCTBridge *)bridge
+{
+  _turboModuleManager = [[RCTTurboModuleManager alloc] initWithBridge:bridge
+                                                             delegate:self
+                                                            jsInvoker:bridge.jsCallInvoker];
+  return RCTAppSetupDefaultJsExecutorFactory(bridge, _turboModuleManager);
+}
+
+#pragma mark RCTTurboModuleManagerDelegate
+
+- (Class)getModuleClassFromName:(const char *)name
+{
+  return RCTCoreModulesClassProvider(name);
+}
+
+- (std::shared_ptr<facebook::react::TurboModule>)getTurboModule:(const std::string &)name
+                                                      jsInvoker:(std::shared_ptr<facebook::react::CallInvoker>)jsInvoker
+{
+  return nullptr;
+}
+
+- (std::shared_ptr<facebook::react::TurboModule>)getTurboModule:(const std::string &)name
+                                                     initParams:(const facebook::react::ObjCTurboModule::InitParams &)params
+{
+  return nullptr;
+}
+
+- (id<RCTTurboModule>)getModuleInstanceFromClass:(Class)moduleClass
+{
+  return RCTAppSetupDefaultModuleFromClass(moduleClass);
+}
+
+#endif
+
 @end