Building Mobile Apps with Expo and Replit

Before getting started, you’ll need:

• A Replit account (free)
• Expo Go app installed on your mobile device
• An Expo EAS account (free)

For publishing to app stores later, you’ll need:

• An Apple Developer account ($99/year) for iOS
• A Google Play Developer account ($25 one-time) for Android

Start by visiting the Expo Template on Replit and selecting “Remix” to create your own copy. This creates a complete copy of the Template in your Replit account, including all the files, configurations, and dependencies.

Select the “Run” button in your Workspace. The Console will display a QR code that links the Expo Go app to your Replit project.

Open the Expo Go app on your phone and scan the QR code displayed in your Workspace. This will load your app directly on your phone. It may take a minute or two for the project to compile.

To help Assistant understand your Expo project better, you can create a custom prompt:

1. Select the settings icon in the Assistant panel
2. Go to “Assistant prompt”
3. Create a prompt that specifies this is an Expo project for building React Native applications

With Assistant, you can describe what you want your app to do, and it will modify the code for you. For example, you might ask: “Create an app that shows me a random image of a cat every time I press a button.”

One of the most powerful features is the ability to continue developing on your mobile device:

1. Open the Replit Mobile App
2. Find your project
3. Use Assistant to make changes and improvements
4. See updates appear in real-time

Before publishing, you’ll need:

• Your Replit App from Part 1
• An Apple Developer account ($99/year) if publishing to iOS
• An iPhone (for iOS deployment)
• An Expo account

Note: After setting up your Apple Developer account, you may need to wait 16-24 hours for Apple to approve your profile.

EAS (Expo Application Services) acts as the interface between your build and Expo, as well as the App Store.

1. Stop your app if it’s running
2. From the dropdown menu in your Workspace, select “EAS init”
3. Log in to your Expo account when prompted
4. Create a new project or select an existing one

This step authenticates your application with your Expo account.

This initialization step helps configure your project and link it to your Apple Developer account.

1. From the dropdown menu, select “EAS update”
2. Wait for the Metro bundler to start and complete the export process

You’ll know this step is successful when you see that bundles have been uploaded and a branch has been created.

Now it’s time to create a preview build for your iOS device.

1. From the dropdown menu, select “EAS publish preview iOS”
2. Enter an iOS bundle identifier (e.g., com.yourname.yourappname)
3. Log in to your App Store Connect account when prompted
4. Select your individual developer team
5. Generate the device distribution certificates when asked

Learn more about iOS certificates and provisioning profiles.

To install development apps on your iPhone, you need to register your device.

1. When prompted, select “website” to register your device
2. Scan the QR code that appears with your iPhone
3. Download the development profile when prompted
4. Go to Settings on your iPhone
5. Select “Profile Downloaded” at the top
6. Install the profile and enter your passcode when prompted
7. Go back to your Workspace and press any key to continue

Expo will now build your app, which takes about 10-15 minutes depending on the complexity of your application.

1. The build will be queued
2. You can check progress in your Expo dashboard under the “Builds” tab
3. Once complete, a new QR code will appear for installing the app

When the build is complete, install the app on your iPhone.

1. Scan the installation QR code with your iPhone
2. Select “Install” when prompted
3. The app will begin installing on your home screen

Before you can open the app, you need to enable developer mode on your iPhone.

1. Go to Settings > Privacy & Security
2. Scroll to the bottom and find “Developer Mode”
3. Toggle it on
4. Restart your device when prompted
5. After restarting, you can open and use your app!