index.js

import { NativeEventEmitter, NativeModules, Platform } from 'react-native';

const { RNFileViewer } = NativeModules;
const eventEmitter = new NativeEventEmitter(RNFileViewer);

let lastId = 0;

function open(path, options = { }) {
  const _options = (typeof options === 'string')
    ? { displayName: options }
    : options;
  const { onDismiss, ...nativeOptions } = _options;

  if (!['android', 'ios'].includes(Platform.OS)) {
    return RNFileViewer.open(path, nativeOptions);
  }

  return new Promise((resolve, reject) => {
    const currentId = ++lastId;

    const openSubscription = eventEmitter.addListener('RNFileViewerDidOpen', ({ id, error }) => {
      if(id === currentId) {
        openSubscription.remove();
        return error ? reject(new Error(error)) : resolve();
      }
    });
    const dismissSubscription = eventEmitter.addListener('RNFileViewerDidDismiss', ({ id }) => {
      if(id === currentId) {
        dismissSubscription.remove();
        onDismiss && onDismiss();
      }
    });

    RNFileViewer.open(path, currentId, nativeOptions);
  });
}

export default { open };