1. Expo Ecology and Core Concepts

In the first chapter, we first quickly establish the overall understanding of Expo from three dimensions: SDK / Expo Go / EAS, and its advantages and trade-offs in real projects.

What is Expo? why choose it

Expo is a development platform and service collection built around React Native, with the goal of allowing you to develop native applications efficiently "just like you do on the Web." It provides: on top of React Native:

• Faster project initialization and development experience (start with zero or less configuration).
• Highly consistent cross-platform API (camera, notifications, file system, sensors, etc.).
• Integrated build, release and hot update service (EAS suite).

Bottom line: If you want to be less entangled with native build details and get your product into the hands of users faster, Expo is a great choice.

Quick start example:

# 1) Initialization
npx create-expo-app my-app

# 2) Enter the project and start the development server
cd my-app
npm run start # Equivalent to npx expo start

# 3) Install Expo Go on your mobile phone to scan the QR code to preview (or use iOS/Android emulator)

You will get a "ready to run" RN application, and common native dependencies (such as icons, device information, screen brightness, etc.) can be used directly through the Expo SDK.

Expo Ecosystem Overview: SDK / Expo Go / EAS

Expo’s ecology can be understood as three layers:

1. Expo SDK (development library)

Expo SDK is a set of JS/TS modules that encapsulate native capabilities, covering common application capabilities:

• UI and themes: expo-router, expo-font, @expo/vector-icons, etc.
• Devices and systems: expo-device, expo-battery, expo-haptics, expo-application.
• Multimedia: expo-image, expo-camera, expo-av.
• Sensors: expo-sensors (acceleration, gyroscope, magnetometer, etc.).
• Notifications and permissions: expo-notifications, expo-permissions (some permissions have been built into each module).
• Storage and files: expo-file-system, expo-secure-store.

Installation and use are usually very straightforward:

npx expo install expo-notifications

import * as Notifications from 'expo-notifications'

await Notifications.scheduleNotificationAsync({
  content: { title: 'Hello Expo' },
  trigger: { seconds: 1 }
})

In the Managed workflow (the two main Expo workflows will be discussed in the next chapter), most SDK modules can be "plug and play", reducing the burden