GitHub - infiniteloopcloud/simpleblue: Simple bluetooth module for Flutter

Features

Supports both Android and iOS.
Small codebase, so breaking changes on the underlying system (ex. bluetooth related updates) can be easily upgraded.
Easy to use, only a few functions to create a working app.

Android

Add the following permissions to your AndroidManifest.xml file. To handle permissions you can use permission_handler package.

<uses-permission android:name="android.permission.BLUETOOTH" android:maxSdkVersion="30" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" android:maxSdkVersion="30" />

<uses-permission android:name="android.permission.BLUETOOTH_SCAN" />
<uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" android:maxSdkVersion="28" />

iOS

Add the following properties to Info.plist in Xcode.

Privacy - Bluetooth Always Usage Description
Privacy - Bluetooth Peripheral Usage Description

Usage

import 'dart:io';

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

import 'package:simpleblue/model/bluetooth_device.dart';
import 'package:simpleblue/simpleblue.dart';

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

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

  @override
  State<MyApp> createState() => _MyAppState();
}

const serviceUUID = null;
const scanTimeout = 15000;

class _MyAppState extends State<MyApp> {
  final _simplebluePlugin = Simpleblue();
  
  bool _isBluetoothTurnedOn = false;
  var devices = <String, BluetoothDevice>{};

  String receivedData = '';

  @override
  void initState() {
    super.initState();

    _simplebluePlugin.listenConnectedDevice().listen((connectedDevice) {
      debugPrint("Connected device: $connectedDevice");

      if (connectedDevice != null) {
        setState(() {
          devices[connectedDevice.uuid] = connectedDevice;
        });
      }

      connectedDevice?.stream?.listen((received) {
        setState(() {
          receivedData += "${DateTime.now().toString()}: $received\n";
        });
      });
    }).onError((err) {
      debugPrint(err);
    });

    WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
      scan();
    });

    _simplebluePlugin.getDevices().then((value) => setState(() {
      for (var device in value) {
        devices[device.uuid] = device;
      }
    }));
    
    _simplebluePlugin.isTurnedOn().then((value) => setState(() {
      _isBluetoothTurnedOn = value ?? false;
    }));

    _simplebluePlugin.listenStateChanges().listen((state) {
      debugPrint('Bluetooth state changed to: $state');

      setState(() {
        _isBluetoothTurnedOn = state == SimpleblueState.on;
      });
    });
  }

  void scan() async {
    final isBluetoothGranted = Platform.isIOS || (await Permission.bluetooth.status) == PermissionStatus.granted ||
        (await Permission.bluetooth.request()) == PermissionStatus.granted;

    if (isBluetoothGranted) {
      print("Bluetooth permission granted");

      final isLocationGranted = Platform.isIOS || (await Permission.location.status) == PermissionStatus.granted ||
          (await Permission.location.request()) == PermissionStatus.granted;

      if (isLocationGranted) {
        print("Location permission granted");
        _simplebluePlugin.scanDevices(serviceUUID: serviceUUID, timeout: scanTimeout).listen((event) {
          setState(() {
            for (var device in event) {
              devices[device.uuid] = device;
            }
          });
        });
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Plugin example app'),
        ),
        body: Column(children: [
          if (_isBluetoothTurnedOn)
            TextButton(
                child: Text('Turn Off Bluetooth'),
                onPressed: () {
                  _simplebluePlugin.turnOff();
                }),
          if (!_isBluetoothTurnedOn)
            TextButton(
                child: Text('Turn On Bluetooth'),
                onPressed: () {
                  _simplebluePlugin.turnOn();
                }),
          TextButton(
              child: Text('Get Devices'),
              onPressed: () {
                _simplebluePlugin.getDevices().then((value) {
                  setState(() {
                    for (var device in value) {
                      devices[device.uuid] = device;
                    }
                  });
                });
              }),
          TextButton(
              child: Text('Scan Devices'),
              onPressed: () {
                scan();
              }),
          Expanded(
            child: buildDevices(),
          ),
          SizedBox(
              height: 200,
              child: Align(
                  alignment: Alignment.topLeft,
                  child: Text(
                    receivedData,
                    style: const TextStyle(fontSize: 10),
                  )))
        ]),
      ),
    );
  }

  final _connectingUUIDs = <String>[];

  Widget buildDevices() {
    final devList = devices.values.toList();
    return ListView.builder(
        itemCount: devList.length,
        itemBuilder: (context, index) {
          final device = devList[index];

          return ListTile(
            onTap: () {
              if (device.isConnected) {
                _simplebluePlugin.disconnect(device.uuid);
              } else {
                setState(() {
                  _connectingUUIDs.add(device.uuid);
                });
                _simplebluePlugin.connect(device.uuid).then((value) {
                  setState(() {
                    _connectingUUIDs.remove(device.uuid);
                  });
                });
              }
            },
            leading: _connectingUUIDs.contains(device.uuid)
                ? Icon(Icons.bluetooth, color: Colors.orange)
                : (device.isConnected
                ? Icon(Icons.bluetooth_connected, color: Colors.blue)
                : Icon(
              Icons.bluetooth,
              color: Colors.grey.shade300,
            )),
            title: Text('${device.name ?? 'No name'}\n${device.uuid}'),
            subtitle: device.isConnected
                ? Row(
              children: [
                TextButton(
                    child: Text('Write 1'),
                    onPressed: () {
                      _simplebluePlugin.write(device.uuid, "sample data".codeUnits);
                    }),
                TextButton(
                    child: Text('Write 2'),
                    onPressed: () {
                      _simplebluePlugin.write(device.uuid, "sample data 2".codeUnits);
                    })
              ],
            )
                : null,
          );
        });
  }
}