Plain code for React Native UI

This project is to show the integration between React Native with a custom native Android component. Reference

Base installation

1. Install node js of version 12.10.0. Reference
2. Install react native with command

## Use npx command instead!
# npm install -g react-native@0.60.4

Installation

1. Clone the project.
2. Cd to the folder and run the command

npm install

3. Install android studio.
4. Checkout React-Native Website getting started to configure Android studio.

# Make sure you create a file .bash_profile in $HOME for MacOS and restart the terminal.
export ANDROID_HOME=$HOME/Library/Android/sdk
export PATH=$PATH:$ANDROID_HOME/emulator
export PATH=$PATH:$ANDROID_HOME/tools
export PATH=$PATH:$ANDROID_HOME/tools/bin
export PATH=$PATH:$ANDROID_HOME/platform-tools

#Windows
set ANDROID_SDK_ROOT=C:\Users\<User name>\AppData\Local\Android\Sdk

Goals

1. Create a layout in pure android, I.E. a native android button. This is the walkthrough to get the module working in React Native project.
2. This project assumes that the React Native project is already created. If not do:

npx react-native init AwesomeProject

NOTE: If you can master this, understanding React Native Module in the official website will be a walk in the park.

Learn

These is how the bridge for the button is created.

1. Start Android studio and open ${PROJECT_NAME}/android/ folder within this project. Allow gradle to run. Fix those android error if exist. If compilation works, the green "Play"/"Debug" button is enabled in Android Studio. Else you will need to make time to fix this...this is the most difficult part for new Android coders.
2. Create the XML (or create a layout via android code) of the layout, Sample is in res/layout/multiplecamerastreamlayout.xml. This is pure Android code which describes an XML to UI.
3. Create a Android view to inflate(changing XML to UI) the XML. Sample is in com.sample_android_ui.CustomView. BONUS: Added a click action.
4. Create a View Manager that will link the Custom View, here is the place to expose the properties. Sample is in com.sample_android_ui.MyCustomReactViewManager. BONUS: Added an optional @ReactProps for parameter passing.
5. Create a ReactPackage and add the react ViewManager into "createViewManagers" method. Sample in com.sample_android_uid.MyCustomPackage.
6. Add the Package into MainApplication to tie the ReactPackage to the loader. Sample in MainApplication.java

  @Override
  protected List<ReactPackage> getPackages() {
    ...
    packages.add(new MyCustomPackage()); //Added here.
    return packages;
  }

7. Define in Javascript, a custom JS view. Sample JS created is CustomView.js

  //File created is named CustomView.js
  import {requireNativeComponent, ViewPropTypes} from 'react-native';
  import PropTypes from 'prop-types';

  module.exports = requireNativeComponent('MyCustomReactViewManager', null);

  //BONUS: Updated to add module.exports = requireNativeComponent('MyCustomReactViewManager', {name: 'message',propTypes: { 'ReactPropName':PropTypes.String }});

  //If View Manager have react properties the code will be module.exports = requireNativeComponent('MyCustomReactViewManager', {name: 'AnynameWillDoItsforLog',propTypes: { 'ReactPropName':PropTypes.* }}); -- Check PropTypes.* is from ReactJS site.

8. Use it in the main Javascript code and remember to set the height/width.

  import CustomView from './CustomView.js';
  ...
    render() {
     return
      ...
      <CustomView style={{height:200, width:200}}/>
      //It can be pointed in issue list (thanks) using flex will make it full screen. Else use height:null
      //BONUS: Updated to create <CustomView style={{height:200, width:200}} message={"Hi there"}/>
      ...;
    }

9. Added an event that receive onClick message, from native code. I.e. from Native code to React Native.

  <CustomView
    ...
    onClick={this._clickEvent}
    />

Run it.

1. Open android and start a device emulator.
2. Once done, do the command.

npx react-native run-android
## Old way was to use global..but version conflict is too prone.
# react-native run-android.

3. Click the button and see the toast box appearing.
4. If there are changes in android. You need to run 'react-native run-android' again.
5. If you opened it in Android Studio, there will be messages in LogCat tab. Filter it by "ANDROID_SAMPLE_UI" to get more information.

Issues

Due to major changes for RN, changing NodeJS and React Native version will impact the project's runtime.

1. If compilation/deployment complains "missing debug.keystore" or "invalid keystore"; either generate a new keystore using Android, or copy an existing React Native's debug.keystore into this project. If using Android studio then generated keystore has the password or secret, keyalias of debug. Generate it via the menu Build->Generate Signed Bundle/Apk and Set deploy build variant as debug.

cp <some exiting RN folder>/android/app/debug.keystore android/app/
#Windows command
#copy ..\<some exiting>\android\app\debug.keystore android\app\

2. If you encountered the error "error Invalid regular expression: /(.\fixtures.|node_modules[]react[]dist[].|" when starting android, downgrade nodejs to 12.10.0.
3. If "react-native start" command keeps failing. Downgrade react-native to 0.60.4. Else use "npx react-native start", which uses package.json defined react-native version instead of global. The command to downgrade is:

  npm uninstall -g react-native
  npm install -g react-native@0.60.4

4. When the application starts as blank; this is a common issue in RN's Android app. In theory, the "react-native start" needs to start before installing the application into android. Do these steps:
   • Close the app sample_reactnative in Android.
   • Open the sample_reactnative app again.
   • Press R and R key again. This refreshes the page.
   • Wait few seconds (10 seconds)