Mobile App Development - Emergent Docs

Mobile App Development on Emergent

Emergent supports cross-platform mobile app development using Expo (React Native framework). Build apps for both iOS and Android from a single codebase! What you can build:

iOS apps
Android apps
Cross-platform apps
Production-ready mobile applications

Requirements

Paid Subscription

Required!Mobile Agent only available on paid plans ($20+/month)Not available on Free Tier

Tech Stack

Fixed Stack:

Frontend: Expo (React Native)
Backend: FastAPI
Database: MongoDB

Supported: Expo/React Native onlyNot Supported: Flutter, native Kotlin, native Swift

How to Access Mobile Agent

Have Paid Subscription

Upgrade to any paid plan ($20+/month)

Go to Home Screen

Return to Emergent home screen

Select Mobile Agent

Click agent dropdown (shows “E1”, “E1.5”, etc.)Choose “Mobile”

Describe Your App

Enter what you want to build:

I want to build a mobile app for [purpose].

Features:
- [Feature 1]
- [Feature 2]
- [Feature 3]

Please create an Expo/React Native app.

Start Building

Click “Start Task”Mobile Agent starts building your app!

What is Expo?

Expo is a framework built on top of React Native that makes mobile development easier. Key Benefits:

Write once, run on iOS and Android
Hot reload during development
Access to native device features
Easy deployment with EAS
Over-the-air updates

What you can access:

Camera and photos
Location services
Push notifications
File system
Sensors (accelerometer, gyroscope)
And much more!

Development Workflow

1. Build with Mobile Agent

Tell the agent what you need:

I need a mobile app for tracking workouts.

Features:
- User authentication
- Log workouts (exercise, sets, reps)
- View workout history
- Charts showing progress
- Dark mode

Backend:
- FastAPI REST API
- MongoDB for data storage
- User accounts

Please build this mobile app with Expo.

The agent will:

Create Expo project structure
Set up React Native components
Build FastAPI backend
Configure MongoDB
Implement all features

2. Test in Preview

During development:

Preview functionality available
Test on development build
Frontend testing subagent for UI tests
Debug and iterate

Best practices:

After each major feature, tell agent:
"Test the [feature name] thoroughly with the testing subagent"

3. Download Your Code

When ready to deploy:

Use Emergent’s file management tools
Download your complete project
Get all mobile app files locally

Your project includes:

Expo app code
FastAPI backend
Configuration files
Assets and resources

Deploying to App Stores

Overview: Using Expo EAS

EAS (Expo Application Services) handles building and submitting your app to stores. What EAS does:

Builds native app binaries (APK/AAB for Android, IPA for iOS)
Submits apps to Google Play Store and Apple App Store
Provides over-the-air updates
All builds happen in the cloud (no Xcode or Android Studio needed!)

Step-by-Step Deployment Guide

Prerequisites

What you’ll need:

Expo Account

Developer Accounts

Google Play: $25 one-timeApple App Store: $99/year(Only need the stores you’re targeting)

Step 1: Set Up EAS Locally

After downloading your code from Emergent:

# Navigate to your mobile app folder
cd your-mobile-app

# Install EAS CLI globally
npm install -g eas-cli

# Login to your Expo account
eas login

# Configure EAS for your project
eas build:configure

This creates eas.json:

{
  "build": {
    "development": {
      "developmentClient": true,
      "distribution": "internal"
    },
    "preview": {
      "distribution": "internal"
    },
    "production": {
      "android": {
        "buildType": "apk"
      }
    }
  }
}

Step 2: Build for Android

Build APK/AAB file:

# Build production Android app
eas build --platform android --profile production

# EAS will ask:
# - Generate a new keystore? → Yes (first time)
# - App identifier? → com.yourname.appname

# Build starts on Expo's servers
# Takes 15-30 minutes

What happens:

Code uploaded to Expo servers
Native Android app compiled
Signed with your keystore
AAB file generated

You’ll get:

Download link for AAB file
Build available in Expo dashboard

Step 3: Build for iOS

Build IPA file:

# Build production iOS app
eas build --platform ios --profile production

# EAS will ask:
# - Bundle identifier? → com.yourname.appname
# - Use Apple credentials? → Yes

# Build starts on Expo's servers
# Takes 20-40 minutes

Requirements:

Apple Developer account
Agree to terms in App Store Connect

You’ll get:

Download link for IPA file
Build available in Expo dashboard

No Mac needed - EAS builds iOS apps in the cloud. You don’t need a Mac or Xcode.

Step 4: Submit to Google Play Store

Create App in Google Play Console

Go to play.google.com/console
Click Create app
Fill in details:
- App name
- Default language
- App type (app or game)
- Free or paid

Prepare Store Listing

Required information:

App description (short and full)
Screenshots (phone, tablet)
Feature graphic
App icon
Privacy policy URL
Content rating questionnaire

Submit with EAS

# Submit to Google Play Store
eas submit --platform android

# Provide when prompted:
# - Google Service Account JSON key
# - Track to submit to (internal, alpha, beta, production)

Getting Service Account Key:

Google Cloud Console → IAM & Admin → Service Accounts
Create service account
Grant “Service Account User” role
Download JSON key file

Review process:

Usually 1-7 days
May require changes
Check Play Console for status

Step 5: Submit to Apple App Store

Create App in App Store Connect

Go to appstoreconnect.apple.com
Click My Apps → + → New App
Fill in details:
- Platform (iOS)
- App name
- Primary language
- Bundle ID
- SKU (unique identifier)

Prepare App Store Listing

Required information:

App description
Keywords
Screenshots (various iPhone sizes)
App preview videos (optional)
Privacy policy URL
Age rating

Submit with EAS

# Submit to Apple App Store
eas submit --platform ios

# Provide when prompted:
# - Apple App Store Connect API Key
# - App Apple ID

Getting API Key:

App Store Connect → Users and Access → Keys
Generate new key with “App Manager” access
Download key file

Review process:

Usually 1-3 days
May be rejected (follow guidelines)
Check App Store Connect for status

App Store Requirements

Google Play Store

Required Information

App name and description
Screenshots (at least 2)
Feature graphic (1024x500)
High-res icon (512x512)
Privacy policy URL
Content rating
Target age group

Technical Requirements

Target API level 33+ (Android 13)
AAB format (not APK for production)
64-bit support
Proper permissions declared
Size limits (varies, generally under 150MB)

Privacy & Safety

Data safety form completed
Privacy policy posted
Permissions justified
COPPA compliance (if targeting children)

Apple App Store

Required Information

App name and subtitle
Description (up to 4000 characters)
Keywords
Screenshots for all device sizes
App icon (1024x1024)
Privacy policy URL
Age rating
Copyright info

Technical Requirements

iOS 13.0+ minimum
Valid provisioning profile
Proper app signing
Size limits (4GB max)
No crashes or bugs

App Review Guidelines

Follow Apple’s guidelines
No private APIs
Proper content rating
Clear app purpose
Functional app (no placeholders)

Over-the-Air (OTA) Updates

Update your app without resubmitting to stores!

What Can Be Updated

Can Update:

JavaScript code
React components
Assets (images, fonts)
App logic and UI

Cannot Update:

Native modules
app.json configuration
Permissions
Native code (Java/Kotlin/Swift)

How to Push Updates

After making changes:

# Make your code changes
# Then push update:

eas update --branch production --message "Bug fixes and improvements"

# Or for specific platforms:
eas update --platform android --branch production
eas update --platform ios --branch production

Users get updates:

Next time they open the app
Automatically in the background
No app store download needed

Perfect for:

Bug fixes
UI tweaks
Feature updates
Content changes

Testing Your Mobile App

During Development (On Emergent)

Use preview and testing tools:

Tell the agent:
"Test the mobile app thoroughly:
- All screens and navigation
- User authentication flow
- Data fetching and display
- Error handling
- Forms and validation

Use the frontend testing subagent."

You can also preview on mobile via the Expo Go app.

After Download (Local Testing)

Expo Go App (Quick Testing):

# Start development server
npx expo start

# Scan QR code with:
# - Expo Go app (iOS/Android)
# - Camera app (iOS)

Benefits:

Instant testing on real device
No build needed
Fast iteration

Limitations:

Some native modules won’t work
Not identical to production

Development Build (Full Testing):

# Build development version
eas build --platform android --profile development
eas build --platform ios --profile development

# Install on device
# Test exactly like production

Benefits:

Full native module support
Identical to production
Test everything

Common Scenarios

Scenario 1: Building First Mobile App

Tell Mobile Agent:

"I want to build a note-taking mobile app.

Features:
- User signup/login
- Create, edit, delete notes
- Organize notes with folders
- Search functionality
- Dark mode
- Offline support

Backend:
- FastAPI REST API
- MongoDB database
- JWT authentication

Please create this as an Expo app."

Scenario 2: App with Camera Access

Tell Mobile Agent:

"Build a photo sharing mobile app.

Features:
- Take photos with camera
- Choose from gallery
- Add filters/effects
- Upload to server
- View feed of photos
- Like and comment

Include proper permissions for camera and photo library.

Please build with Expo."

Scenario 3: Location-Based App

Tell Mobile Agent:

"Create a location tracking mobile app.

Features:
- Track user's current location
- Show on map
- Save favorite locations
- Get directions
- Location history
- Share location

Include location permissions.

Please build with Expo."

Troubleshooting

Build Failures

Issue: EAS build fails Solutions:

# Check build logs
eas build:list

# View specific build
eas build:view [build-id]

# Common fixes:
# 1. Check app.json configuration
# 2. Verify dependencies are compatible
# 3. Check for native module issues
# 4. Review error messages carefully

Submission Rejected

Google Play:

Follow rejection reasons exactly
Update app accordingly
Resubmit

Apple App Store:

Review rejection details
Fix issues mentioned
Reply to reviewer if needed
Resubmit

Updates Not Appearing

Check:

# View published updates
eas update:list --branch production

# Check specific update
eas update:view [update-id]

# Republish if needed
eas update --branch production --message "Republish"

EAS Pricing

Free Tier

30 builds per month
Unlimited EAS Updates
Community support

Good for:

Development and testing
Small projects
Learning

Production Plan

$29/month
More builds
Priority build queue
Better for active development

Good for:

Professional apps
Multiple apps
Frequent updates

Enterprise

Custom pricing
Unlimited builds
Dedicated support
SLA guarantees

Good for:

Large teams
Mission-critical apps
Many apps

Best Practices

Development

Start simple:

Build core features first
Test thoroughly
Add advanced features later

Test on real devices:

Use Expo Go during development
Build development builds for full testing
Test on both iOS and Android

Use version control:

Commit changes regularly
Use Git for version management
Tag releases

Deployment

Before submitting:

Tested all features thoroughly
No console errors or warnings
Proper app icons and splash screens
Privacy policy in place
Store listing prepared
Screenshots captured
Tested on multiple devices

Build strategy:

Development → Internal Testing → Beta → Production

Update strategy:

Use OTA updates for JavaScript changes
Rebuild for native changes
Test updates before pushing

Maintenance

Monitor your app:

Check crash reports
Review user feedback
Monitor performance
Track analytics

Update regularly:

Bug fixes via OTA updates
Feature updates with app versions
Security patches promptly

Resources

Expo Documentation

App Store Guidelines

Emergent Support

Discord: discord.gg/VzKfwCXC4A
Email: support@emergent.sh

Getting Help

From Emergent

For Mobile Agent issues:

Contact Emergent support:
- Discord community
- Email support
- Describe your mobile app requirements

For code/feature help:

Tell the Mobile Agent:
"I need help with [specific issue in mobile app].
Current behavior: [describe]
Expected behavior: [describe]
Please debug and fix."

From Expo

For EAS issues:

For build issues:

Review build logs carefully
Check Expo documentation
Search existing issues
Ask in Expo community

Quick Reference

Essential Commands

# Setup
npm install -g eas-cli
eas login
eas build:configure

# Building
eas build --platform android --profile production
eas build --platform ios --profile production
eas build --platform all --profile production

# Submitting
eas submit --platform android
eas submit --platform ios

# Updating
eas update --branch production --message "Description"

# Checking
eas build:list
eas update:list

Development Workflow

1. Build with Mobile Agent on Emergent
   ↓
2. Test in Preview
   ↓
3. Download code locally
   ↓
4. Set up EAS
   ↓
5. Build with EAS
   ↓
6. Test builds on devices
   ↓
7. Submit to stores
   ↓
8. Wait for approval
   ↓
9. App goes live!
   ↓
10. Push updates with EAS Update

Remember

Mobile Agent requires paid subscription Only Expo/React Native supported EAS handles building and deployment No Mac needed for iOS builds OTA updates for JavaScript changes Test thoroughly before submitting Both stores require developer accounts Review processes take 1-7 days

Getting started: Build your app with Mobile Agent, download the code, then use EAS to deploy to app stores. The Mobile Agent handles the complex Expo setup for you!

Next Steps

Upgrade to Paid Plan

If on Free Tier, upgrade to access Mobile Agent

Build Your App

Use Mobile Agent to create your Expo app

Download Code

Get your complete mobile app code

Set Up EAS

Install EAS CLI and configure

Deploy

Build and submit to app stores!

Have questions? Contact Emergent support for help with mobile development!

​Mobile App Development on Emergent

​Requirements

Paid Subscription

Tech Stack

​How to Access Mobile Agent

​What is Expo?

​Development Workflow

​1. Build with Mobile Agent

​2. Test in Preview

​3. Download Your Code

​Deploying to App Stores

​Overview: Using Expo EAS

​Step-by-Step Deployment Guide

​Prerequisites

Expo Account

Developer Accounts

​Step 1: Set Up EAS Locally

​Step 2: Build for Android

​Step 3: Build for iOS

​Step 4: Submit to Google Play Store

​Create App in Google Play Console

​Prepare Store Listing

​Submit with EAS

​Step 5: Submit to Apple App Store

​Create App in App Store Connect

​Prepare App Store Listing

​Submit with EAS

​App Store Requirements

​Google Play Store

​Apple App Store

​Over-the-Air (OTA) Updates

​What Can Be Updated

​How to Push Updates

​Testing Your Mobile App

​During Development (On Emergent)

​After Download (Local Testing)

​Common Scenarios

​Scenario 1: Building First Mobile App

​Scenario 2: App with Camera Access

​Scenario 3: Location-Based App

​Troubleshooting

​Build Failures

​Submission Rejected

​Updates Not Appearing

​EAS Pricing

​Free Tier

​Production Plan

​Enterprise

​Best Practices

​Development

​Deployment

​Maintenance

​Resources

​Expo Documentation

​App Store Guidelines

​Emergent Support

​Getting Help

​From Emergent

​From Expo

​Quick Reference

​Essential Commands

​Development Workflow

​Remember

​Next Steps

Mobile App Development on Emergent

Requirements

How to Access Mobile Agent

What is Expo?

Development Workflow

1. Build with Mobile Agent

2. Test in Preview

3. Download Your Code

Deploying to App Stores

Overview: Using Expo EAS

Step-by-Step Deployment Guide

Prerequisites

Step 1: Set Up EAS Locally

Step 2: Build for Android

Step 3: Build for iOS

Step 4: Submit to Google Play Store

Create App in Google Play Console

Prepare Store Listing

Submit with EAS

Step 5: Submit to Apple App Store

Create App in App Store Connect

Prepare App Store Listing

Submit with EAS

App Store Requirements

Google Play Store

Apple App Store

Over-the-Air (OTA) Updates

What Can Be Updated

How to Push Updates

Testing Your Mobile App

During Development (On Emergent)

After Download (Local Testing)

Common Scenarios

Scenario 1: Building First Mobile App

Scenario 2: App with Camera Access

Scenario 3: Location-Based App

Troubleshooting

Build Failures

Submission Rejected

Updates Not Appearing

EAS Pricing

Free Tier

Production Plan

Enterprise

Best Practices

Development

Deployment

Maintenance

Resources

Expo Documentation

App Store Guidelines

Emergent Support

Getting Help

From Emergent

From Expo

Quick Reference

Essential Commands

Development Workflow

Remember

Next Steps