react-native save image

gistfile1.js

import React from 'react';
import { StyleSheet, Button, View, SafeAreaView, Text, Alert } from 'react-native';
import { WebView } from 'react-native-webview';
import * as MediaLibrary from 'expo-media-library';
import * as FileSystem from 'expo-file-system';

const App = () => {
  // save image
  const SaveToPhone = async (imagedata: string) => {
    // get the base64 image string
    const base64Code = imagedata.split('data:image/png;base64,')[1];
    // create the image file
    const filename = FileSystem.documentDirectory + 'receipt.png';
    await FileSystem.writeAsStringAsync(filename, base64Code, {
      encoding: FileSystem.EncodingType.Base64
    });

    const permission = await MediaLibrary.requestPermissionsAsync();
    if (permission.granted) {
      try {
        // save the image
        await MediaLibrary.saveToLibraryAsync(filename);
      } catch (error) {
        console.log(error);
      }
    } else {
      console.log('Need Storage permission to save file');
    }
  };

  const handleOnMessage = (event) => {
    if (event && event.nativeEvent && event.nativeEvent.data) {
      const data = JSON.parse(event.nativeEvent.data);
      if (data.type === 'download') {
        SaveToPhone(data.imagedata);
      }
    }
  };
  return (
    <SafeAreaView style={styles.container}>
      <View>
        <Text style={styles.title}> TEST WESTERN UNION </Text>
        <Button title="BUTTON TEST" onPress={() => Alert.alert('Button pressed')} />
      </View>
      <WebView onMessage={handleOnMessage} source={{ uri: 'https://checkout-western-union.dingdev.com/' }} />
    </SafeAreaView>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    marginHorizontal: 16
  },
  title: {
    textAlign: 'center',
    marginVertical: 8
  },
  fixToText: {
    flexDirection: 'row',
    justifyContent: 'space-between'
  },
  separator: {
    marginVertical: 8,
    borderBottomColor: '#737373',
    borderBottomWidth: StyleSheet.hairlineWidth
  }
});

export default App;