THIS IS A FORK VERSION OF FLUTTER_BLUE(这是一个 fork 版本，使用前请注意！)

Since the original flutter_blue is no longer maintained, I forked the original repository and continued its maintenance for newer versions of Flutter:

• Added a method to retrieve bonded(paired) devices, allowing these devices to connect without scanning(Android ONLY).
• Introduced more intuitive functions to directly obtain the device connection status and MTU, instead of getting the first status from a stream.
• Fixed a crash issue on higher versions of Android caused by a redundant UUID class.
• Corrected the issue where the timeout setting in the original connect method would not throw an exception in the current await process.
• Resolved the problem with the example not running on higher versions of Android.

由于原先的 flutter_blue 不再维护，我 fork 了原仓库并针对新版本 flutter 继续维护：

• 增加了获取已绑定设备(已配对设备)的方法，已配对设备可以不需要扫描就能连接（仅安卓）。
• 增加了更直观的直接获取设备连接状态和 MTU 的函数，而不是从流获得第一个状态。
• 修复了在高版本安卓上由于一个无用的 UUID 类导致的闪退问题。
• 修复了原来的 connect 方法中的 timeout 设置并不会在当前的 await 流程中抛出异常的问题。
• 修复了示例在高版本安卓上运行的问题。

Introduction

FlutterBlue is a bluetooth plugin for Flutter, a new app SDK to help developers build modern multi-platform apps.

Alpha version

This library is actively developed alongside production apps, and the API will evolve as we continue our way to version 1.0.

Please be fully prepared to deal with breaking changes. This package must be tested on a real device.

Having trouble adapting to the latest API? I'd love to hear your use-case, please contact me.

Cross-Platform Bluetooth LE

FlutterBlue aims to offer the most from both platforms (iOS and Android).

Using the FlutterBlue instance, you can scan for and connect to nearby devices (BluetoothDevice). Once connected to a device, the BluetoothDevice object can discover services (BluetoothService), characteristics (BluetoothCharacteristic), and descriptors (BluetoothDescriptor). The BluetoothDevice object is then used to directly interact with characteristics and descriptors.

Usage

Obtain an instance

FlutterBlue flutterBlue = FlutterBlue.instance;

Scan for devices

// Start scanning
flutterBlue.startScan(timeout: Duration(seconds: 4));

// Listen to scan results
var subscription = flutterBlue.scanResults.listen((results) {
    // do something with scan results
    for (ScanResult r in results) {
        print('${r.device.name} found! rssi: ${r.rssi}');
    }
});

// Stop scanning
flutterBlue.stopScan();

Connect to a device

// Connect to the device
await device.connect();

// Disconnect from device
device.disconnect();

Discover services

List<BluetoothService> services = await device.discoverServices();
services.forEach((service) {
    // do something with service
});

Read and write characteristics

// Reads all characteristics
var characteristics = service.characteristics;
for(BluetoothCharacteristic c in characteristics) {
    List<int> value = await c.read();
    print(value);
}

// Writes to a characteristic
await c.write([0x12, 0x34])

Read and write descriptors

// Reads all descriptors
var descriptors = characteristic.descriptors;
for(BluetoothDescriptor d in descriptors) {
    List<int> value = await d.read();
    print(value);
}

// Writes to a descriptor
await d.write([0x12, 0x34])

Set notifications and listen to changes

await characteristic.setNotifyValue(true);
characteristic.value.listen((value) {
    // do something with new value
});

Read the MTU and request larger size

final mtu = await device.mtu.first;
await device.requestMtu(512);

Note that iOS will not allow requests of MTU size, and will always try to negotiate the highest possible MTU (iOS supports up to MTU size 185)

Getting Started

Change the minSdkVersion for Android

Flutter_blue is compatible only from version 19 of Android SDK so you should change this in android/app/build.gradle:

Android {
  defaultConfig {
     minSdkVersion: 19

Add permissions for Bluetooth

We need to add the permission to use Bluetooth and access location:

Android

In the android/app/src/main/AndroidManifest.xml let’s add:

    <!-- Request legacy Bluetooth permissions on older devices. -->
    <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.FOREGROUND_SERVICE" />
    <uses-permission android:name="android.permission.ACCESS_BACKGROUND_LOCATION"/>
    <!-- Needed only if your app looks for Bluetooth devices.
         You must add an attribute to this permission, or declare the
         ACCESS_FINE_LOCATION permission, depending on the results when you
         check location usage in your app. -->
    <uses-permission android:name="android.permission.BLUETOOTH_SCAN" />

    <!-- Needed only if your app makes the device discoverable to Bluetooth
         devices. -->
    <uses-permission android:name="android.permission.BLUETOOTH_ADVERTISE" />

    <!-- Needed only if your app communicates with already-paired Bluetooth
         devices. -->
    <uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
 <application

IOS

In the ios/Runner/Info.plist let’s add:

	<dict>
	    <key>NSBluetoothAlwaysUsageDescription</key>
	    <string>Need BLE permission</string>
	    <key>NSBluetoothPeripheralUsageDescription</key>
	    <string>Need BLE permission</string>
	    <key>NSLocationAlwaysAndWhenInUseUsageDescription</key>
	    <string>Need Location permission</string>
	    <key>NSLocationAlwaysUsageDescription</key>
	    <string>Need Location permission</string>
	    <key>NSLocationWhenInUseUsageDescription</key>
	    <string>Need Location permission</string>

For location permissions on iOS see more at: https://developer.apple.com/documentation/corelocation/requesting_authorization_for_location_services

Reference

FlutterBlue API

	Android	iOS	Description
scan	✅	✅	Starts a scan for Bluetooth Low Energy devices.
state	✅	✅	Stream of state changes for the Bluetooth Adapter.
isAvailable	✅	✅	Checks whether the device supports Bluetooth.
isOn	✅	✅	Checks if Bluetooth functionality is turned on.

BluetoothDevice API

	Android	iOS	Description
connect	✅	✅	Establishes a connection to the device.
disconnect	✅	✅	Cancels an active or pending connection to the device.
discoverServices	✅	✅	Discovers services offered by the remote device as well as their characteristics and descriptors.
services	✅	✅	Gets a list of services. Requires that discoverServices() has completed.
state	✅	✅	Stream of state changes for the Bluetooth Device.
mtu	✅	✅	Stream of mtu size changes.
requestMtu	✅		Request to change the MTU for the device.

BluetoothCharacteristic API

	Android	iOS	Description
read	✅	✅	Retrieves the value of the characteristic.
write	✅	✅	Writes the value of the characteristic.
setNotifyValue	✅	✅	Sets notifications or indications on the characteristic.
value	✅	✅	Stream of characteristic's value when changed.

BluetoothDescriptor API

	Android	iOS	Description
read	✅	✅	Retrieves the value of the descriptor.
write	✅	✅	Writes the value of the descriptor.

Troubleshooting

When I scan using a service UUID filter, it doesn't find any devices.

Make sure the device is advertising which service UUID's it supports. This is found in the advertisement packet as UUID 16 bit complete list or UUID 128 bit complete list.