reading rtf file using Dart and Flutter. Answer to this question: https://stackoverflow.com/questions/78045540/how-to-read-and-write-rtf-file-in-flutter-app/78045582#78045582

main.dart

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

void main() {
  debugInvertOversizedImages = true;
  runApp(const MaterialApp(home: RftReaderScreen()));
}

class RftReaderScreen extends StatefulWidget {
  const RftReaderScreen({Key? key}) : super(key: key);

  @override
  State<RftReaderScreen> createState() => _RftReaderScreenState();
}

class _RftReaderScreenState extends State<RftReaderScreen> {
  String? _res;

  @override
  void initState() {
    super.initState();
    
    // Here we are accessing example.rtf file
    // loadString method fetches all the text from example.rtf file 
    // after loading all the text we are setting to our local variable
    rootBundle.loadString("assets/example.rtf").then((value) => setState(() {
          _res = value;
        }));
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Text(_res ?? "Loading . . ."),
      ),
    );
  }
}