react-native-webview: iOS Release Build Failed to load Local HTML/JS/CSS Files in React Native WebView

Description

I’m trying to load SPA with AngularJS and HTML in React Native WebView.

import React, {Component} from 'react';
import {Platform, StyleSheet, Text, View} from 'react-native';
import { WebView } from "react-native-webview";

export default class App extends Component{
  render() {
    return (
      <WebView
        useWebKit={true}
        originWhitelist={['*']}

        source={ Platform.OS === 'ios' ? require('./MyPackage/www/index.html') : {uri: 'file:///android_asset/www/index.html'} } 

        onLoadProgress={e=>console.log(e.nativeEvent.progress)}
        javaScriptEnabled={true}
        domStorageEnabled={true}
        nativeConfig={{ props: { webContentsDebuggingEnabled: true } }}
        setAllowFileAccessFromFileURLs={true}
        setAllowUniversalAccessFromFileURLs={true}
      />
   );
  } 
}

For Android, I’m copying the content of MyPackage inside android_asset folder as:

task copyReactNativeHTML(type: Copy) {
    from '../../MyPackage/'
    into 'src/main/assets'
}
gradle.projectsEvaluated {
    bundleDebugJsAndAssets.dependsOn(copyReactNativeHTML)
    bundleReleaseJsAndAssets.dependsOn(copyReactNativeHTML)
}

^The above is working fine for Android Debug/Release Build without any error.

For iOS, I’m keeping MyPackage folder at root level of the project. It’s working fine in iOS Debug Build but when I tried to load it in iOS Release Build it’s throwing following error:

[Error] Failed to load resource: The requested URL was not found on this server.
file:///var/containers/Bundle/Application/4074A848-9399-4CD1-B7B6-58C4DDBFF1C6/SampleReactNativeApp.app/assets/MyPackage/www/css/bootstrap.css

[Error] Failed to load resource: The requested URL was not found on this server. 
file:///var/containers/Bundle/Application/4074A848-9399-4CD1-B7B6-58C4DDBFF1C6/SampleReactNativeApp.app/assets/MyPackage/www/js/angular.js

^Here the id (074A848-9399-4CD1-B7B6-58C4DDBFF1C6) is randomly getting generated every time in the above Error and SampleReactNativeApp is my project/app name.

I tried debugging it in Safari Browser and found that none of the resources(JS/CSS) are getting loaded which I’m including in index.html

Environment

React Native Environment Info:
    System:
      OS: macOS Sierra 10.12.6
      CPU: (4) x64 Intel(R) Core(TM) i5-7400 CPU @ 3.00GHz
      Memory: 138.34 MB / 8.00 GB
      Shell: 3.2.57 - /bin/bash
    Binaries:
      Node: 11.1.0 - /usr/local/bin/node
      npm: 6.4.1 - /usr/local/bin/npm
      Watchman: 4.9.0 - /usr/local/bin/watchman
    SDKs:
      iOS SDK:
        Platforms: iOS 11.2, macOS 10.13, tvOS 11.2, watchOS 4.2
      Android SDK:
        API Levels: 21, 22, 23, 24, 25, 26, 27, 28
        Build Tools: 21.1.2, 22.0.1, 23.0.1, 23.0.2, 23.0.3, 24.0.0, 24.0.1, 24.0.2, 24.0.3, 25.0.0, 25.0.1, 25.0.2, 25.0.3, 26.0.0, 26.0.1, 26.0.2, 26.0.3, 27.0.0, 27.0.1, 27.0.2, 27.0.3, 28.0.0, 28.0.0, 28.0.0, 28.0.1, 28.0.2, 28.0.3
        System Images: android-28 | Google APIs Intel x86 Atom
    IDEs:
      Android Studio: 3.2 AI-181.5540.7.32.5056338
      Xcode: 9.2/9C40b - /usr/bin/xcodebuild
    npmPackages:
      react: 16.6.0-alpha.8af6728 => 16.6.0-alpha.8af6728 
      react-native: 0.57.3 => 0.57.3 
    npmGlobalPackages:
      react-native-cli: 2.0.1