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Overview

The initExecutorch function initializes the React Native ExecuTorch library by configuring a resource fetcher adapter. This is a required setup step that must be called before using any hooks or modules.

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Import

import { initExecutorch, ExecutorchConfig } from 'react-native-executorch';

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Function Signature

function initExecutorch(config: ExecutorchConfig): void

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Parameters

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config
ExecutorchConfig
required
Configuration object containing the resource fetcher adapter

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ResourceFetcherAdapter Interface

The resource fetcher adapter must implement the following interface:
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fetch
function
required
Fetches resources (remote URLs, local files, or embedded assets) and stores them locally
fetch(
  callback: (downloadProgress: number) => void,
  ...sources: ResourceSource[]
): Promise<string[] | null>
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readAsString
function
required
Reads file contents as a string
readAsString(path: string): Promise<string>

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Usage Examples

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Expo App

import { initExecutorch } from 'react-native-executorch';
import { ExpoResourceFetcher } from '@react-native-executorch/expo-resource-fetcher';

// Initialize at app startup (e.g., in App.tsx)
initExecutorch({
  resourceFetcher: new ExpoResourceFetcher(),
});

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Bare React Native App

import { initExecutorch } from 'react-native-executorch';
import { BareResourceFetcher } from '@react-native-executorch/bare-resource-fetcher';

// Initialize at app startup (e.g., in index.js)
initExecutorch({
  resourceFetcher: new BareResourceFetcher(),
});

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Custom Resource Fetcher

import { initExecutorch, ResourceFetcherAdapter } from 'react-native-executorch';

class CustomResourceFetcher implements ResourceFetcherAdapter {
  async fetch(
    callback: (progress: number) => void,
    ...sources: ResourceSource[]
  ): Promise<string[] | null> {
    // Custom implementation for fetching resources
    const paths: string[] = [];
    
    for (const source of sources) {
      // Download or locate resource
      const localPath = await this.downloadResource(source);
      paths.push(localPath);
      
      // Report progress
      callback(paths.length / sources.length);
    }
    
    return paths;
  }
  
  async readAsString(path: string): Promise<string> {
    // Custom implementation for reading files
    return await FileSystem.readAsStringAsync(path);
  }
  
  private async downloadResource(source: ResourceSource): Promise<string> {
    // Implementation details...
    return '/path/to/downloaded/file';
  }
}

initExecutorch({
  resourceFetcher: new CustomResourceFetcher(),
});

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cleanupExecutorch

import { cleanupExecutorch } from 'react-native-executorch';

// Reset the resource fetcher adapter
cleanupExecutorch();
Cleans up the current resource fetcher setup. Primarily used for testing purposes.

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Notes

You must call initExecutorch before using any hooks or modules in the library. Failure to initialize will result in a ResourceFetcherAdapterNotInitialized error.
Call initExecutorch only once at application startup. Multiple calls will override the previous configuration.

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Error Handling

If you attempt to use any hook or module without initializing, you’ll receive: 
ResourceFetcherAdapterNotInitialized: ResourceFetcher adapter is not initialized. 
Please call initExecutorch({ resourceFetcher: ... }) with a valid adapter.

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See Also

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