How to save downloaded files and view in File app using React Native in iOS?

I am using react-native-fs to download files from server and save them. Once they are downloaded I am using react-native-file-viewer to open them. This process totally works fine: I am able to download and open it in the viewer, but I am not able to save the file in the File application from the viewer, though I can save in iCloud but not in the iPhone.The downloaded file is stored in a place like

/var/mobile/Containers/Data/Application/CCF6CD16-A62A-48BB-92F3-3021195CFE0C/Documents/react-native-pdf.pdf

but this is not shown in the File app.

The code I am using to download and view the file is as follows

    RNFS.downloadFile({      fromUrl: 'http://www.mywebsite.com/react-native-pdfurl.pdf',      toFile: `${RNFS.DocumentDirectoryPath}/react-native-pdfurl.pdf`,    }).promise.then((r) => {      console.log('yo yo yo ');      this.setState({ isDone: true });      const path = `${RNFS.DocumentDirectoryPath}/react-native-pdfurl.pdf`;      FileViewer.open(path)      .then(() => {          // success      })      .catch(error => {          // error      });      RNFS.readDir(RNFS.DocumentDirectoryPath).then(files => {          console.log(files);      })        .catch(err => {            console.log(err.message, err.code);        });    });

The readDir gets me the name path of the file saved. But this is not reflected in any folder in the File application.My question is how can I save the file in a way that it shows in the File application.