Dart/Flutter: Imports all contacts into .vcf file

Question

I'm trying to copy contacts from an Android device and save them in .vcf format(such as 'Contacts.vcf') on the user's internal storage.

• Using flutter_contacts: ^1.1.7+1 package, I've accessed and converted each contact to vCard.
• Using the path_provider package, I've been able to write on the user's internal storage(creating and storing 'Contacts.vcf' file).

HERE IS MY CODE:

import 'dart:io';
import 'package:flutter/material.dart';
import 'package:flutter_contacts/flutter_contacts.dart';
import 'package:path_provider/path_provider.dart';
import 'package:permission_handler/permission_handler.dart';

class HomeScreen extends StatefulWidget {
  const HomeScreen({super.key});

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}


class _HomeScreenState extends State<HomeScreen> {
  List<String> vCardsList = [];

  void getAllContactsFromDeviceAndSaveTovcfFile() async {
    bool isPermissionGranted = await FlutterContacts.requestPermission();
    List<Contact> contacts = await FlutterContacts.getContacts();
    for (Contact contact in contacts) {
      vCardsList.add(contact.toVCard());
    }
    for (int i = 0; i < vCardsList.length; i++) {
    }

    PermissionStatus permissionStatus = await Permission.storage.request();
    final Directory? externalStorageDirectoryPath =
        await getExternalStorageDirectory();
    if (externalStorageDirectoryPath != null) {
      File file = File('${externalStorageDirectoryPath.path}/contacts.vcf');

      for (int i = 0; i < vCardsList.length; i++) {
        print(vCardsList.length);

        file.writeAsString(vCardsList[i], mode: FileMode.writeOnlyAppend);
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    getAllContactsFromDeviceAndSaveTovcfFile();
    return const Scaffold(
      body: PlaceHolder(),
    );
  }
}

Finally, I'm trying to copy the List of vCards into this 'Contacts.vcf' file(I'm expecting that all the vCards would be copied to this 'Contacts.vcf' file and I would be able to import this file in the future to import all my contacts on my device).

Any help would be appreciated. Moreover, if you think there is a better way to achieve my final goal, that would be very helpful.

Thanks in Advance!