How to download images to local gallery or files in React native

  const downloadFile = () => {    let date = new Date();    let FILE_URL = fileUrl;    let file_ext = getFileExtention(FILE_URL);    const {config, fs} = RNFetchBlob;    let RootDir = fs.dirs.DownloadDir;    let options = {      fileCache: true,      addAndroidDownloads: {        path:          RootDir +'/file_'+          Math.floor(date.getTime() + date.getSeconds() / 2) +"."+          file_ext,        description: 'downloading file...',        notification: true,        useDownloadManager: true,      },    };    config(options)      .fetch('GET', FILE_URL)      .then(res => {        console.log('res -> ', JSON.stringify(res));        Alert.alert('File Downloaded Successfully.');      });  };  const getFileExtention = (fileUrl: string) => {    return /[.]/.exec(fileUrl) ? /[^.]+$/.exec(fileUrl) : undefined;  };  // Sharing  const letShare = async () => {    const shareOptions = {      message: 'This is a test message',      url: fileUrl    };    try {      const shareResponse = await Share.open(shareOptions);    } catch (error) {      console.log('error', error);    }  };

I am new in React native and trying to create the image share and download page where I am not getting download it in ios and android gallery and while sharing how to share the base 64 format of any image.