AWS Amplify auth

To use AWS amplify within your application, you must have the Amplify CLI. Open a terminal and paste the code below to install the Amplify CLI.

Install Amplify 

npm install -g @aws-amplify/cli 

After a successful installation of the Amplify CLI, run the following code to configure the CLI.

amplify configure

• Specify an AWS region
• Adding the accessKeyId and the secretAccessKey of the user created
• Adding an AWS profile

Setting up a React Native app

install expo

npm install --g expo-cli

expo init aws-amplify-authentication-tutorial

choose default blank template.

Adding AWS Amplify to a React Native application

 cd C:\svn\aws-amplify-authentication-tutorial

amplify init

npm install aws-amplify aws-amplify-react-native @react-native-community/netinfo

Open the App.js file in your code editor and add the following lines of code after the last import statement:

import Amplify from 'aws-amplify';
import config from './aws-exports';
Amplify.configure({
  ...config,
  Analytics: {
    disabled: true,
  },
});

Adding authentication with Amazon Cognito
amplify add auth
Choose the default configurationamplify push

amplify push
At this point, we can integrate the authentication service in our application. The Amplify Framework provides built-in, customizable UI components that are easy to integrate, which helps streamline the process.
Go to your App.js and add the following line below the import statements:
import { withAuthenticator } from 'aws-amplify-react-native';
withAuthenticator is a higher-order component that automatically detects the authentication state of the application and updates the UI.
Change the default export at the end of App.js to the following:
export default withAuthenticator(App)
run
expo start