AppDelegate.m

RCTRootView *rootView = [[RCTRootView alloc] initWithBundleURL:jsCodeLocation
                                                      moduleName:@"MCDJ"
                                               initialProperties:nil
                                                   launchOptions:launchOptions];
  
  self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];

  UIViewController *rootViewController = [[UIViewController alloc] init];
  rootViewController.view = rootView;
  
  self.window.rootViewController = rootViewController;
  
  // Set reference to class property
  self.rootViewController = rootViewController;

  [self.window makeKeyAndVisible];