Understanding Native Modules in React Native

The battery level, the camera and the fingerprint sensor of a phone are all controlled by the operating system, and it offers them only to code written for that system: Swift or Objective-C on iOS, Kotlin or Java on Android. Your React Native code is JavaScript, so it cannot reach them directly. A piece of native code that exposes such a feature as a function your JavaScript can call is called a native module.

This chapter uses native modules to reach the camera, location, motion sensors, Bluetooth and NFC, background tasks, biometric authentication and the file system