flutter_blue_plus 1.20.4

Flutter plugin for connecting and communicationg with Bluetooth Low Energy devices, on Android, iOS, and MacOS.

example/lib/main.dart

// Copyright 2017-2023, Charles Weinberger & Paul DeMarco.
// All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'dart:async';

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

import 'screens/bluetooth_off_screen.dart';
import 'screens/scan_screen.dart';

void main() {
  runApp(const FlutterBlueApp());
}

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

  @override
  State<FlutterBlueApp> createState() => _FlutterBlueAppState();
}

class _FlutterBlueAppState extends State<FlutterBlueApp> {
  BluetoothAdapterState _adapterState = BluetoothAdapterState.unknown;

  late StreamSubscription<BluetoothAdapterState> _adapterStateStateSubscription;

  @override
  void initState() {
    super.initState();
    _adapterStateStateSubscription = FlutterBluePlus.adapterState.listen((state) {
      _adapterState = state;
      setState(() {});
    });
  }

  @override
  void dispose() {
    _adapterStateStateSubscription.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    Widget screen = _adapterState == BluetoothAdapterState.on
        ? const ScanScreen()
        : BluetoothOffScreen(adapterState: _adapterState);

    return MaterialApp(
      color: Colors.lightBlue,
      home: screen,
      navigatorObservers: [BluetoothAdapterStateObserver()],
    );
  }
}

class BluetoothAdapterStateObserver extends NavigatorObserver {
  StreamSubscription<BluetoothAdapterState>? _adapterStateSubscription;

  @override
  void didPush(Route route, Route? previousRoute) {
    super.didPush(route, previousRoute);
    if (route.settings.name == '/DeviceScreen') {
      // Start listening to Bluetooth state changes when a new route is pushed
      _adapterStateSubscription ??= FlutterBluePlus.adapterState.listen((state) {
        if (state != BluetoothAdapterState.on) {
          // Pop the current route if Bluetooth is off
          navigator?.pop();
        }
      });
    }
  }

  @override
  void didPop(Route route, Route? previousRoute) {
    super.didPop(route, previousRoute);
    // Cancel the subscription when the route is popped
    _adapterStateSubscription?.cancel();
    _adapterStateSubscription = null;
  }
}