How to add Expo to a native app using the integrated approach

// package <your-package-here>

import android.os.Build

import com.facebook.react.ReactActivity
import com.facebook.react.ReactActivityDelegate
import com.facebook.react.defaults.DefaultNewArchitectureEntryPoint.fabricEnabled
import com.facebook.react.defaults.DefaultReactActivityDelegate

import expo.modules.ReactActivityDelegateWrapper

class MyReactActivity : ReactActivity() {

  /**
   * Returns the name of the main component registered from JavaScript. This is used to schedule
   * rendering of the component.
   */
  override fun getMainComponentName(): String = "main"

  /**
   * Returns the instance of the [ReactActivityDelegate]. We use [DefaultReactActivityDelegate]
   * which allows you to enable New Architecture with a single boolean flags [fabricEnabled]
   */
  override fun createReactActivityDelegate(): ReactActivityDelegate {
    return ReactActivityDelegateWrapper(
          this,
          BuildConfig.IS_NEW_ARCHITECTURE_ENABLED,
          object : DefaultReactActivityDelegate(
              this,
              mainComponentName,
              fabricEnabled
          ){})
  }
}

require File.join(File.dirname(`node --print "require.resolve('expo/package.json')"`), "scripts/autolinking")
require File.join(File.dirname(`node --print "require.resolve('react-native/package.json')"`), "scripts/react_native_pods")

require 'json'

platform :ios, '16.4'
install! 'cocoapods',
  :deterministic_uuids => false

prepare_react_native_project!

target 'HelloWorld' do
  use_expo_modules!

  config_command = [
    'npx',
    'expo-modules-autolinking',
    'react-native-config',
    '--json',
    '--platform',
    'ios'
  ]
  config = use_native_modules!(config_command)

  use_frameworks! :linkage => ENV['USE_FRAMEWORKS'].to_sym if ENV['USE_FRAMEWORKS']

  use_react_native!(
    :path => config[:reactNativePath],
    :hermes_enabled => true,
    # An absolute path to your application root.
    :app_path => "#{Pod::Config.instance.installation_root}/..",
    :privacy_file_aggregation_enabled => true,
  )

  post_install do |installer|
    react_native_post_install(
      installer,
      config[:reactNativePath],
      :mac_catalyst_enabled => false,
    )
  end
end

import UIKit
import React
import React_RCTAppDelegate
import ReactAppDependencyProvider

class ReactNativeViewController: UIViewController {
  var reactNativeFactory: RCTReactNativeFactory?
  var reactNativeFactoryDelegate: RCTReactNativeFactoryDelegate?

  override func viewDidLoad() {
    super.viewDidLoad()
    reactNativeFactoryDelegate = ReactNativeDelegate()
    reactNativeFactoryDelegate!.dependencyProvider = RCTAppDependencyProvider()
    reactNativeFactory = RCTReactNativeFactory(delegate: reactNativeFactoryDelegate!)
    view = reactNativeFactory!.rootViewFactory.view(withModuleName: "HelloWorld")

  }
}

class ReactNativeDelegate: RCTDefaultReactNativeFactoryDelegate {
    override func sourceURL(for bridge: RCTBridge) -> URL? {
      self.bundleURL()
    }

    override func bundleURL() -> URL? {
      #if DEBUG
      RCTBundleURLProvider.sharedSettings().jsBundleURL(forBundleRoot: ".expo/.virtual-metro-entry")
      #else
      Bundle.main.url(forResource: "main", withExtension: "jsbundle")
      #endif
    }

}

import UIKit

class ViewController: UIViewController {

  var reactViewController: ReactViewController?

  override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view.
    self.view.backgroundColor = .systemBackground

    let button = UIButton()
    button.setTitle("Open React Native", for: .normal)
    button.setTitleColor(.systemBlue, for: .normal)
    button.setTitleColor(.blue, for: .highlighted)
    button.addAction(UIAction { [weak self] _ in
      guard let self else { return }
      if reactViewController == nil {
       reactViewController = ReactViewController()
      }
      present(reactViewController!, animated: true)
    }, for: .touchUpInside)
    self.view.addSubview(button)

    button.translatesAutoresizingMaskIntoConstraints = false
    NSLayoutConstraint.activate([
      button.leadingAnchor.constraint(equalTo: self.view.leadingAnchor),
      button.trailingAnchor.constraint(equalTo: self.view.trailingAnchor),
      button.centerXAnchor.constraint(equalTo: self.view.centerXAnchor),
      button.centerYAnchor.constraint(equalTo: self.view.centerYAnchor),
    ])
  }
}