appShare.js

import React, { Component } from 'react'
import Share from 'react-native-share'
import RNFetchBlob from "rn-fetch-blob";
import RNFS from 'react-native-fs'

export default class EventShare extends Component {
  constructor(props) {
    super(props)

    this.state = {
      shareEventLoading: false
    }
  }

  shareEvent = async () => {
    await this.setState({
      shareEventLoading: true
    })

    const shareOptions = {
      title: 'My Share',
      message: 'To have more information, please access the app.'
    }

    let filePath
    RNFetchBlob.config({ fileCache: true })
      .fetch('GET', this.props.event.photos[0])
      .then(resp => {
        filePath = resp.path()
        return resp.readFile('base64')
      })
      .then(async base64Data => {
        shareOptions.url = 'data:image/png;base64,' + base64Data
        try {
          await Share.open(shareOptions)
          await RNFS.unlink(filePath)
          await this.setState({
            shareEventLoading: false
          })
        } catch (error) {
          await this.setState({
            shareEventLoading: false
          })
        }
      })
  }

  render() {
    ...
  }
}