React Native Create Custom Component/Library

Take a look at the official Facebook guide Native Modules Setup. It explains how to start:

$ yarn global add create-react-native-module
$ create-react-native-module MyLibrary

This will generate a README.md with next steps as follows:

react-native-my-library

Getting started

$ npm install react-native-my-library --save

Mostly automatic installation

$ react-native link react-native-my-library

Usage

import my-library from 'react-native-my-library';

// TODO: What to do with the module? 
my-library;

1. Command: new-library

React-native-cli offers the new-library command:

react-native new-library --name <YourNewLibraryName>

Calling this will generate a sample library in your Libraries directory by copying sample file over from the react-native library.

2. Developing

React Native has a couple docs specifically for writing Native Modules and Native UI Components, depending on what you want to achieve.

3. Link component

Link your component once you're done by following the instructions you already mentioned.

Using the react-native Module setup

$ yarn global add create-react-native-module
$ create-react-native-module NameOfLibrary

A template would be generated for you, you can write your custom UI code in the index.js and expand on it as deemed fit.