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Relive: removed "expo" require from dist/index.js. This is because otherwise metro bundler doesn't bundle without Expo installed

NPM

expo-asset-utils

Utilities for converting files into Expo Assets. Uses:

  • Caching remote files
  • Parsing asset-library:// files from ios CameraRoll
  • Parsing local files from Android's file system
  • Preparing assets to be rendered in GL 😁

Installation

yarn add expo-asset-utils

Usage

Import the library into your JavaScript file:

import AssetUtils from 'expo-asset-utils';

Functions

resolveAsync

Given a reference to some asset, this will return a promise that resolves to an Expo.Asset that has been cached.

  • Expo asset: Expo.Asset.fromModule(require('./image.png'))
  • static resource: require('./image.png')
  • remote image: 'https://upload.wikimedia.org/wikipedia/en/1/17/Batman-BenAffleck.jpg'
  • local file: 'file:///var/image.png'
  • asset library file: 'asset-library:///var/image.png'
  • React Native Image source: {uri: 'https://upload.wikimedia.org/wikipedia/en/1/17/Batman-BenAffleck.jpg'}
Property Type Description
fileReference Expo.Asset, number, string, {uri: string} This will resolve into a downloaded Expo.Asset

uriAsync

Given a reference to some asset, this will return a promise that resolves to a local uri.

Property Type Description
fileReference Expo.Asset, number, string, {uri: string} This will resolve into a downloaded Expo.Asset

copyAssetToSameDirectoryWithNewNameAsync

Given a reference to some asset, and a name (ex: 'file.png') this will copy that asset to the same directory with the provided name. This is used for libraries that parse files by extracting the relative path and appending some arbitrary file name to that path.

Property Type Description
fileReference Expo.Asset, number, string, {uri: string} This will resolve into a downloaded Expo.Asset
name string The file will be copied with this name

fromUriAsync

Given a file URI string, this will return an Expo.Asset that hasn't been downloaded yet.

Property Type Description
remoteUri string This remote URI will be downloaded and it's file info will be gathered
fileName string This will be assigned to the Expo.Asset.name

fileInfoAsync

Given a file URI string, this will cache the file and collect the MD5 hash

Property Type Description
uri string This URI (local, remote, asset library) will be cached and it's MD5 hash will be retrieved
name string This will be assigned to the Expo.Asset.name, if not provided the last component of the uri will be used
base64forImageUriAsync

Given a image URI string, this will return a base64 encoded string and the image size: { data: string, size: { width: number, height: number } }

Property Type Description
uri string This URI will be converted to base64
arrayFromObject

Given an object this will recursively surface the items into an array. Generally used for preloading assets.

Property Type Description
object Object This will be converted into an array
cacheAssetsAsync

Given a image URI string, this will return a base64 encoded string and the image size: { data: string, size: { width: number, height: number } }

Property Type Description
images Array These will be loaded using React Native Image if they are strings, and Expo preloading if they are static resources
files Array An Array of static resources that will be downloaded using Expo preloading
fonts Array An Array of { [fontFamily]: staticResource } that will be loaded using Expo.Font and then be available through fontFamily style props

Example

import AssetUtils from 'expo-asset-utils';

const remoteImage = 'https://upload.wikimedia.org/wikipedia/en/1/17/Batman-BenAffleck.jpg';
const asset = await AssetUtil.resolveAsync(remoteImage);
const { localUri, width, height } = asset;

Checkout this Snack!

TODO

  • Parse HEIC from iOS 11