React Native - Image Cache

I read the document about the React Native image component in this site and got some questions: https://facebook.github.io/react-native/docs/image.html

1. If I use the source property to display image. Will the image be cached and save to disk after download?

2. If yes, what is the cache policy?

3. If I want to save the downloaded image to disk. Is it better to use getSize or prefetch method to do it?

Many thanks.

React native image component NSURLRequest's cache policy as described here. Personally I use RNFetchBlob to cache images as described here. You can also checkout this component.

You may be interested in my higher order component module that adds performance related image caching and "permanent cache" functionality to the native <Image> component.

React Native Image Cache HOC

Tl;DR Code Example:

import imageCacheHoc from 'react-native-image-cache-hoc';
const CacheableImage = imageCacheHoc(Image);

export default class App extends Component<{}> {
  render() {
    return (
      <View style={styles.container}>
        <Text style={styles.welcome}>Welcome to React Native!</Text>
        <CacheableImage style={styles.image} source={{uri: 'https://i.redd.it/rc29s4bz61uz.png'}} />
        <CacheableImage style={styles.image} source={{uri: 'https://i.redd.it/hhhim0kc5swz.jpg'}} permanent={true} />
      </View>
  );
  }
}

The first image will be cached until the total local cache grows past 15 MB (by default) then cached images are deleted oldest first until total cache is below 15 MB again.

The second image will be stored to local disk permanently. People use this as a drop in replacement for shipping static image files with your app.

That should handle your requirement out of the box. Hope it helps!