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Level 3 · Native Capabilities & Polish

Levels 1 and 2 used React Native as a cross-platform UI layer. Level 3 is where it becomes a mobile app: it uses the camera and GPS, asks for permissions properly, sends notifications, animates at the display's frame rate even while JavaScript is busy, responds to gestures, works with screen readers, and — when no library does what you need — talks to Swift and Kotlin code you write yourself.

It starts with the model that makes all of this make sense: which thread runs what, and how the New Architecture (JSI, Fabric, TurboModules) connects JavaScript to native code. Then each lesson uses that model: device APIs are native modules, Reanimated's worklets run on the UI thread, Gesture Handler recognises touches natively, and your own Expo module is a TurboModule-style native module. The level finishes with development builds and config plugins — the tools that let you add any native code to an Expo app — and a field-notes app that uses the camera, location and offline sync.

Prerequisites: Levels 1 and 2. Several lessons need a development build (lesson 9 explains how) or a physical device; each lesson says so where it applies. Some features — push delivery, a real camera, GPS — can't be fully exercised on a simulator, and the lessons are explicit about that.

Modules

  1. Under the Hood: Threads, JSI & the New Architecture — the runtime model behind every other lesson.
  2. Device APIs: Camera, Location & Haptics — Expo modules for hardware, with real-world caveats.
  3. Permissions Done Right — asking at the right moment, handling "no", and the platform rules.
  4. Local & Push Notifications — scheduling reminders, push tokens and handling taps.
  5. Animations with Animated & Reanimated — shared values, worklets and layout animations.
  6. Gestures with React Native Gesture Handler — pan, swipe-to-complete and composing gestures with animations.
  7. Accessibility in React Native — roles, labels, focus, dynamic type and reduced motion.
  8. Writing a Native Module with the Expo Modules API — Swift and Kotlin functions callable from TypeScript.
  9. Development Builds, Prebuild & Config Plugins — leaving Expo Go without leaving Expo.
  10. Project — Field Notes with Camera, Location & Offline Sync — capture geotagged notes offline and sync them when the network returns.