AppRegistry

AppRegistry is the JS entry point to running all React Native apps. App root components should register themselves with AppRegistry.registerComponent, then the native system can load the bundle for the app and run it when ready by invoking AppRegistry.runApplication.

Methods

`registerComponent()`

static registerComponent(
  appKey: string,
  componentProvider: () => React.ComponentType<any>,
  section?: boolean
): string

Registers an app’s root component. This is the main method you’ll use in your app’s entry file. Parameters:

appKey: String name for the application
componentProvider: Function that returns a React component
section: Optional boolean to register as a section

Returns:

The appKey that was registered

Example:

import { AppRegistry } from 'react-native';
import App from './App';

AppRegistry.registerComponent('MyApp', () => App);

`runApplication()`

static runApplication(
  appKey: string,
  appParameters: any,
  displayMode?: number
): void

Loads the JavaScript bundle and runs the app. Usually called from native code. Parameters:

appKey: The string name of the app to run
appParameters: Object containing:
- initialProps: Props to pass to the root component
- rootTag: The native root view tag
- fabric: Whether Fabric renderer is enabled
displayMode: Optional display mode configuration

Example:

import { AppRegistry } from 'react-native';

AppRegistry.runApplication('MyApp', {
  initialProps: { userId: '123' },
  rootTag: 1,
});

`unmountApplicationComponentAtRootTag()`

static unmountApplicationComponentAtRootTag(rootTag: number): void

Stops an application when a view should be destroyed. Should be used as a pair with runApplication. Parameters:

rootTag: The root tag that was passed to runApplication

Example:

import { AppRegistry } from 'react-native';

AppRegistry.unmountApplicationComponentAtRootTag(1);

`registerHeadlessTask()`

static registerHeadlessTask(
  taskKey: string,
  taskProvider: () => (taskData: any) => Promise<void>
): void

Register a headless task - code that runs without a UI (e.g., handling push notifications in the background). Parameters:

taskKey: Unique string identifier for the task
taskProvider: Function that returns an async task function

Example:

import { AppRegistry } from 'react-native';

const MyTask = async (taskData) => {
  console.log('Headless task running with data:', taskData);
  // Perform background work
};

AppRegistry.registerHeadlessTask('MyTask', () => MyTask);

`registerCancellableHeadlessTask()`

static registerCancellableHeadlessTask(
  taskKey: string,
  taskProvider: () => (taskData: any) => Promise<void>,
  taskCancelProvider: () => () => void
): void

taskKey: Unique string identifier for the task
taskProvider: Function that returns an async task function
taskCancelProvider: Function that returns a cancellation function

Example:

import { AppRegistry } from 'react-native';

let taskCancelled = false;

const MyTask = async (taskData) => {
  for (let i = 0; i < 100; i++) {
    if (taskCancelled) break;
    // Do work
  }
};

AppRegistry.registerCancellableHeadlessTask(
  'MyCancellableTask',
  () => MyTask,
  () => () => { taskCancelled = true; }
);

`startHeadlessTask()`

static startHeadlessTask(
  taskId: number,
  taskKey: string,
  data: any
): void

Starts a headless task. Only called from native code. Parameters:

taskId: Numeric ID for this task instance
taskKey: The registered task key
data: Data to pass to the task

`cancelHeadlessTask()`

static cancelHeadlessTask(
  taskId: number,
  taskKey: string
): void

Cancels a running headless task. Only called from native code. Parameters:

taskId: The task instance ID
taskKey: The registered task key

`setSurfaceProps()`

static setSurfaceProps(
  appKey: string,
  appParameters: any,
  displayMode?: number
): void

Updates initial props for a surface that’s already rendered. Parameters:

appKey: The registered app key
appParameters: New parameters/props
displayMode: Optional display mode

`getAppKeys()`

static getAppKeys(): string[]

Returns an array of all registered app keys. Returns:

Array of registered application keys

`getRunnable()`

static getRunnable(appKey: string): Runnable | undefined

Gets the runnable function for a registered app. Parameters:

appKey: The app key to look up

Returns:

The runnable function or undefined if not found

Typical Usage

In your app’s entry file (usually index.js):

import { AppRegistry } from 'react-native';
import App from './App';
import { name as appName } from './app.json';

AppRegistry.registerComponent(appName, () => App);

Core APIs

Hooks

Interaction

Accessibility & Internationalization

Developer Tools

Networking

Storage

Android APIs

iOS APIs

Methods

`registerComponent()`

`runApplication()`

`unmountApplicationComponentAtRootTag()`

`registerHeadlessTask()`

`registerCancellableHeadlessTask()`

`startHeadlessTask()`

`cancelHeadlessTask()`

`setSurfaceProps()`

`getAppKeys()`

`getRunnable()`

Typical Usage

​Methods

​registerComponent()

​runApplication()

​unmountApplicationComponentAtRootTag()

​registerHeadlessTask()

​registerCancellableHeadlessTask()

​startHeadlessTask()

​cancelHeadlessTask()

​setSurfaceProps()

​getAppKeys()

​getRunnable()

​Typical Usage

Methods

`registerComponent()`

`runApplication()`

`unmountApplicationComponentAtRootTag()`

`registerHeadlessTask()`

`registerCancellableHeadlessTask()`

`startHeadlessTask()`

`cancelHeadlessTask()`

`setSurfaceProps()`

`getAppKeys()`

`getRunnable()`

Typical Usage