Usage

This page documents the resource fetcher APIs exposed by react-native-executorch-expo-resource-fetcher and react-native-executorch-bare-resource-fetcher. These adapters handle downloading and managing model files on disk.

info

All examples below use ExpoResourceFetcher. If you're on bare React Native, replace the import with:

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

The public API is identical between both adapters.

fetch

Fetches resources (remote URLs, local files, or embedded assets) and stores them locally for use by React Native ExecuTorch.

Reference

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

const uris = await ExpoResourceFetcher.fetch(
  (progress) => console.log('Total progress:', progress),
  'https://.../lfm2_5.pte',
  'https://.../tokenizer.json'
);

Parameters

• callback: (downloadProgress: number) => void - Optional callback to track progress of all downloads, reported between 0 and 1.
• ...sources: ResourceSource[] - Multiple resources that can be strings, asset references, or objects.

Returns

Promise<string[] | null>:

• If the fetch was successful, it returns a promise which resolves to an array of local file paths for the downloaded/stored resources (without file:// prefix).
• If the fetch was interrupted by pauseFetching or cancelFetching, it returns a promise which resolves to null.

info

If the resource is an object, it will be saved as a JSON file on disk.

pauseFetching

Pauses an ongoing download.

info

Bare Resource Fetcher doesn't support this feature on Android.

Reference

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

const uris = ExpoResourceFetcher.fetch(
  (progress) => console.log('Total progress:', progress),
  'https://.../lfm2_5.pte',
  'https://.../tokenizer.json'
).then((uris) => {
  console.log('URI resolved to: ', uris); // null, since we paused
});

await ExpoResourceFetcher.pauseFetching(
  'https://.../lfm2_5.pte',
  'https://.../tokenizer.json'
);

Parameters

• ...sources: ResourceSource[] - The resource identifiers used when calling fetch.

Returns

Promise<void> – A promise that resolves once the download is paused.

resumeFetching

info

Bare Resource Fetcher doesn't support this feature on Android.

Resumes a paused download.

Reference

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

const uris = ExpoResourceFetcher.fetch(
  (progress) => console.log('Total progress:', progress),
  'https://.../lfm2_5.pte',
  'https://.../tokenizer.json'
).then((uris) => {
  console.log('URI resolved as: ', uris); // null, since we paused
});

await ExpoResourceFetcher.pauseFetching(
  'https://.../lfm2_5.pte',
  'https://.../tokenizer.json'
);

const resolvedUris = await ExpoResourceFetcher.resumeFetching(
  'https://.../lfm2_5.pte',
  'https://.../tokenizer.json'
);
// resolvedUris resolves to file paths, unless paused/cancelled again

Parameters

• ...sources: ResourceSource[] - The resource identifiers used when calling fetch.

Returns

Promise<string[] | null>:

• If the fetch was successful, it returns a promise which resolves to an array of local file paths for the downloaded resources (without file:// prefix).
• If the fetch was again interrupted by pauseFetching or cancelFetching, it returns a promise which resolves to null.

info

You can also resume a paused download by calling fetch again with the same sources. However, resumeFetching is faster as it resumes from where it left off.

cancelFetching

Cancels an ongoing or paused download.

Reference

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

const uris = ExpoResourceFetcher.fetch(
  (progress) => console.log('Total progress:', progress),
  'https://.../lfm2_5.pte',
  'https://.../tokenizer.json'
).then((uris) => {
  console.log('URI resolved as: ', uris); // null, since we cancelled
});

await ExpoResourceFetcher.cancelFetching(
  'https://.../lfm2_5.pte',
  'https://.../tokenizer.json'
);

Parameters

• ...sources: ResourceSource[] - The resource identifiers used when calling fetch().

Returns

Promise<void> – A promise that resolves once the download is cancelled.

deleteResources

Deletes downloaded resources from the local filesystem.

Reference

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

await ExpoResourceFetcher.deleteResources('https://.../lfm2_5.pte');

Parameters

• ...sources: ResourceSource[] - The resource identifiers used when calling fetch.

Returns

Promise<void> – A promise that resolves once all specified resources have been removed.

getFilesTotalSize

Fetches the combined size of remote files. Works only for remote URLs.

Reference

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

const totalSize = await ExpoResourceFetcher.getFilesTotalSize(
  'https://.../lfm2_5.pte',
  'https://.../tokenizer.json'
);

Parameters

• ...sources: ResourceSource[] - The resource identifiers (URLs).

Returns

Promise<number> – A promise that resolves to the combined size of files in bytes.

listDownloadedFiles

Lists all files downloaded by React Native ExecuTorch.

Reference

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

const filesUris = await ExpoResourceFetcher.listDownloadedFiles();

Returns

Promise<string[]> - A promise that resolves to an array of URIs for all downloaded files.

listDownloadedModels

Lists all downloaded model files (.pte).

Reference

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

const modelsUris = await ExpoResourceFetcher.listDownloadedModels();

Returns

Promise<string[]> - A promise that resolves to an array of URIs for all downloaded model files.