Unlock the Power of React Native: A Step-by-Step Guide to User Authentication

The Challenge of Custom Authentication Systems

Many organizations have custom authentication systems that require integration with mobile apps. React Native, like React, is unopinionated, leaving developers with numerous decisions to make when implementing complex functionality. To overcome this challenge, we’ll build a demo application that showcases user authentication using JSON Web Tokens (JWT).

What is a JSON Web Token (JWT)?

In simple terms, a JWT is a secure way to exchange information between parties using the JSON format. After successful authentication, we receive two tokens: an access token and a refresh token. The access token is sent with every authenticated request, while the refresh token is used to obtain a new access token when the existing one expires.

const accessToken = 'access_token_here';
const refreshToken = 'efresh_token_here';

The Demo Application

Our demo app has a single feature: displaying a random picture of a cat. To access this feature, users must be authenticated. We’ll use a backend implemented with Express and MongoDB, which exposes four API endpoints: register, login, refreshToken, and cat.

• Register: Create a new user account
• Login: Authenticate an existing user
• Refresh Token: Obtain a new access token when the existing one expires
• Cat: Display a random picture of a cat (only accessible after successful authentication)

Implementing Authentication in React Native

To manage the authentication state, we’ll use the Context API and react-native-keychain to persist tokens securely. We’ll also use axios to make HTTP requests and interceptors to send the access token in the Authorization header. The axios-auth-refresh package will handle token refreshment and retry failed requests.

import { createContext, useState, useEffect } from 'eact';
import { Keychain } from 'eact-native-keychain';
import axios from 'axios';

const AuthContext = createContext();

const AuthProvider = ({ children }) => {
  const [accessToken, setAccessToken] = useState(null);
  const [refreshToken, setRefreshToken] = useState(null);

  useEffect(() => {
    // Check for tokens in the Keychain
    Keychain.getAccessToken().then((token) => {
      setAccessToken(token);
    });
    Keychain.getRefreshToken().then((token) => {
      setRefreshToken(token);
    });
  }, []);

  // Implement login, refreshToken, and logout functionality
  //...

  return (
    
      {children}
    
  );
};

The Authentication Flow

When the app launches, we’ll check for tokens in the Keychain. If none exist, we’ll render the Login screen. Otherwise, we’ll display the Dashboard. The Login component will call the API with the public instance of Axios, and upon successful login, we’ll save the access and refresh tokens into the Keychain.

1. App launches and checks for tokens in the Keychain
2. If no tokens exist, render the Login screen
3. Login component calls the API with Axios
4. Upon successful login, save access and refresh tokens into the Keychain
5. Display the Dashboard

Taking it to the Next Level

While our demo app provides a solid foundation for user authentication, there are many ways to improve it. We can add navigation, enhance error handling, and optimize API requests. With React Native, the possibilities are endless.

• Add navigation to simplify user flow
• Enhance error handling to provide better feedback to users
• Optimize API requests to improve performance
• And many more…

Learn more about React Native authentication