AppDelegate.h

#import <UIKit/UIKit.h>
#import <UMReactNativeAdapter/UMModuleRegistryAdapter.h>
#import <React/RCTBridgeDelegate.h>

@interface AppDelegate : UIResponder <UIApplicationDelegate, RCTBridgeDelegate>

@property (nonatomic, strong) UMModuleRegistryAdapter *moduleRegistryAdapter;
@property (nonatomic, strong) UIWindow *window;

@end

AppDelegate.m

#import "AppDelegate.h"

#import <React/RCTBundleURLProvider.h>
#import <React/RCTRootView.h>

#import <UMCore/UMModuleRegistry.h>
#import <UMReactNativeAdapter/UMNativeModulesProxy.h>
#import <UMReactNativeAdapter/UMModuleRegistryAdapter.h>

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
  self.moduleRegistryAdapter = [[UMModuleRegistryAdapter alloc] initWithModuleRegistryProvider:[[UMModuleRegistryProvider alloc] init]];
  RCTBridge *bridge = [[RCTBridge alloc] initWithDelegate:self launchOptions:launchOptions];
  RCTRootView *rootView = [[RCTRootView alloc] initWithBridge:bridge moduleName:@"MyApp" initialProperties:nil];
  rootView.backgroundColor = [[UIColor alloc] initWithRed:1.0f green:1.0f blue:1.0f alpha:1];

  self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
  UIViewController *rootViewController = [UIViewController new];
  rootViewController.view = rootView;
  self.window.rootViewController = rootViewController;
  [self.window makeKeyAndVisible];
  return YES;
}

- (NSArray<id<RCTBridgeModule>> *)extraModulesForBridge:(RCTBridge *)bridge
{
  NSArray<id<RCTBridgeModule>> *extraModules = [_moduleRegistryAdapter extraModulesForBridge:bridge andExperience:nil];
  // If you'd like to export some custom RCTBridgeModules that are not Unimodules modules, add them here!
  return extraModules;
}

- (NSURL *)sourceURLForBridge:(RCTBridge *)bridge {
#ifdef DEBUG
  return [[RCTBundleURLProvider sharedSettings] jsBundleURLForBundleRoot:@"index" fallbackResource:nil];
#else
  return [[NSBundle mainBundle] URLForResource:@"main" withExtension:@"jsbundle"];
#endif
}

@end