Connecting Expo Apps to AWS Amplify Backend

Introduction

AWS Amplify simplifies backend integration with features like authentication, GraphQL APIs, and storage. This guide configures Amplify in Expo.

Prerequisites

• Expo project
• AWS account with Amplify CLI installed

Step 1: Install Amplify Libraries

npm install aws-amplify @aws-amplify/auth @aws-amplify/api-graphql
npm install -g @aws-amplify/cli

Step 2: Initialize Amplify Project

amplify init
# Choose default settings: JS, React Native, managed workflow

Step 3: Add Authentication

amplify add auth
# Default configuration
amplify push

Step 4: Configure Amplify in Expo

Create src/aws-exports.js generated by Amplify.

Update App.js:

import React, { useEffect } from 'react';
import { withAuthenticator } from 'aws-amplify-react-native';
import Amplify from 'aws-amplify';
import awsconfig from './src/aws-exports';

Amplify.configure({
  ...awsconfig,
  Analytics: {
    disabled: true, // Disable Analytics if not needed
  },
});

function App() {
  return (
    // Your app UI
  );
}

export default withAuthenticator(App);

Step 5: Add GraphQL API

amplify add api
# Choose GraphQL, default schema
amplify push

Use generated API module:

import { API, graphqlOperation } from "aws-amplify";
import { createPost } from "./src/graphql/mutations";
import { listPosts } from "./src/graphql/queries";

export async function fetchPosts() {
  const result = await API.graphql(graphqlOperation(listPosts));
  return result.data.listPosts.items;
}

export async function addPost(title, content) {
  await API.graphql(
    graphqlOperation(createPost, { input: { title, content } })
  );
}

Step 6: Add Storage (S3)

amplify add storage
# Content (Images), auth only
amplify push

Use Storage module:

import { Storage } from "aws-amplify";

export async function uploadImage(uri) {
  const response = await fetch(uri);
  const blob = await response.blob();
  const key = `images/${Date.now()}.png`;
  await Storage.put(key, blob, { contentType: "image/png" });
  return key;
}

Summary

AWS Amplify accelerates backend integration for authentication, GraphQL APIs, and storage in Expo apps with minimal boilerplate.