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ACR Reactive BluetoothLE Plugin

Easy to use, cross platform, REACTIVE BluetoothLE Plugin for ALL platforms!

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Change Log - November 17, 2018

PLATFORMS

Platform	Version
Android	4.3+
iOS	7+
macOS	Latest
tvOS	Latest
Windows UWP	16299+

UWP is still in beta!

Client cannot disconnect
Server WIP
PRs only during beta please!

FEATURES

Scan for advertisement packets and devices (with full control of the scanning features)
Monitor adapter status (and control it on android)
Open Bluetooth settings screen
Persistent connections
Deals with the Android threading and defect headaches
Discover services, characteristics, & descriptors
Read, write, & receive notifications for characteristics
Support for reliable write transactions
Read & write descriptors
Request & monitor MTU changes
Connect to heart rate monitors
Deals with most of the Android fubars
Manages iOS backgrounding by allowing hooks to WhenWillRestoreState
Control the adapter state on Android
Pair with devices
GATT Server and Advertising Support
- Advertising
  - Manufactuer Data
  - Service UUIDs
- Charactertistics
  - Read
  - Write
  - Notify & Broadcast
  - Manage Subscribers
  - Status Replies
Android Issues
- We manage the GATT 133 (mostly, hopefully)
- Don't like the serial way you have to work with BLE, don't worry, we cover that too. Read/Write away!
- Don't know what thread to run a method on? Don't worry - we got that covered.... just make the read/write call and relax

SETUP

Be sure to install the Plugin.BluetoothLE nuget package in all of your main platform projects as well as your core/NETStandard project

Android

Add the following to your AndroidManifest.xml PLEASE NOTE THAT YOU HAVE TO REQUEST THESE PERMISSIONS USING Activity.RequestPermission or a Plugin

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

<!--this is necessary for Android v6+ to get the device name and address-->
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

iOS

If you want to use background BLE periperhals, add the following to your Info.plist

<key>UIBackgroundModes</key>
<array>
    <!--for connecting to devices (client)-->
	<string>bluetooth-central</string>

    <!--for server configurations if needed-->
	<string>bluetooth-peripheral</string>
</array>

<!--To add a description to the Bluetooth request message (on iOS 10 this is required!)-->
<key>NSBluetoothPeripheralUsageDescription</key>
<string>YOUR CUSTOM MESSAGE</string>

HOW TO USE - CLIENT BASICS

// discover some devices
CrossBleAdapter.Current.Scan().Subscribe(scanResult => {});

// Once finding the device/scanresult you want
scanResult.Device.Connect();

Device.WhenAnyCharacteristicDiscovered().Subscribe(characteristic => {
    // read, write, or subscribe to notifications here
    var result = await characteristic.Read(); // use result.Data to see response
    await characteristic.Write(bytes);

    characteristic.EnableNotifications();
    characteristic.WhenNotificationReceived().Subscribe(result => {
    	//result.Data to get at response
    });
});

HOW TO USE - SERVER BASICS

Most important things - you should setup all of your services and characteristics BEFORE you Start() the server!

var server = CrossBleAdapter.Current.CreateGattServer();
var service = server.AddService(Guid.NewGuid(), true);

var characteristic = service.AddCharacteristic(
    Guid.NewGuid(),
    CharacteristicProperties.Read | CharacteristicProperties.Write | CharacteristicProperties.WriteWithoutResponse,
    GattPermissions.Read | GattPermissions.Write
);

var notifyCharacteristic = service.AddCharacteristic
(
    Guid.NewGuid(),
    CharacteristicProperties.Indicate | CharacteristicProperties.Notify,
    GattPermissions.Read | GattPermissions.Write
);

IDisposable notifyBroadcast = null;
notifyCharacteristic.WhenDeviceSubscriptionChanged().Subscribe(e =>
{
    var @event = e.IsSubscribed ? "Subscribed" : "Unsubcribed";

    if (notifyBroadcast == null)
    {
        this.notifyBroadcast = Observable
            .Interval(TimeSpan.FromSeconds(1))
            .Where(x => notifyCharacteristic.SubscribedDevices.Count > 0)
            .Subscribe(_ =>
            {
                Debug.WriteLine("Sending Broadcast");
                var dt = DateTime.Now.ToString("g");
                var bytes = Encoding.UTF8.GetBytes(dt);
                notifyCharacteristic.Broadcast(bytes);
            });
    }
});

characteristic.WhenReadReceived().Subscribe(x =>
{
    var write = "HELLO";

    // you must set a reply value
    x.Value = Encoding.UTF8.GetBytes(write);

    x.Status = GattStatus.Success; // you can optionally set a status, but it defaults to Success
});
characteristic.WhenWriteReceived().Subscribe(x =>
{
    var write = Encoding.UTF8.GetString(x.Value, 0, x.Value.Length);
    // do something value
});

await server.Start(new AdvertisementData
{
    LocalName = "TestServer"
});

DOCUMENTATION

Adapter
Device
Services
Characteristics
Descriptors
Platform Specifics
- Android
- iOS
- UWP
Extensions
- Heart Rate
- Beacons
Server
- Advertising
- GATT

FAQ

Q. Why is everything reactive instead of events/async

I wanted event streams as I was scanning devices. I also wanted to throttle things like characteristic notification feeds. Lastly, was the proper cleanup of events and resources.

Q. Why are Device.Connect, Characteristic.Read, and Descriptor.Read observable when async would do just fine?

True, but observables with RX are actually awaitable as well and far easier to chain into other things.

Q. Why are devices cleared on a new scan?

Some platforms yield a "new" device and therefore new hooks. This was observed on some android devices.

Q. My characteristic read/writes/notifications are not working

If you store your discovered characteristics in your own variables, make sure to refresh them with each (re)connect

Q. I cannot see the device name in Android 6+

You need to enable permissions for android.permission.ACCESS_COARSE_LOCATION

Q. I cannot see the device name when scanning in the background on iOS

This is the work of iOS. The library cannot fix this. You should scan by service UUIDs instead

Q. Does this support Bluetooth v2?

No - please read about bluetooth specifications before using this library. LE (Low Energy) is part of the v4.0 specification.

Q. Why can't I disconnect devices selectively in the GATT server?

On android, you can, but exposing this functionality in xplat proves challenging since iOS does not support A LOT of things

Q. Why can't I configure the device name on Android?

Please read the advertising docs on this

GENERAL RULES TO FOLLOW

DO NOT reuse services, characteristics, and descriptors between connnections
DO catch errors in your subscriptions (ie. Reads/Writes)
DO set timeouts on all connected operations using Observable.Timeout(TimeSpan). Timeout throws errors that you must also manage!
DO NOT manage reconnection yourself
DO NOT scan with the adapter while you have an open GATT connection
If you have a TX/RX setup using Notify/Write, use 2 characteristics, not one

CONTRIBUTORS

Thank you for all your help

Marius Bloemhof for all the extensive testing
Jesse Jiang for all the PRs
Jelle Damen for the wonderful icons
MKGNZ for the UWP work

jiangjiangjiang2018/bluetoothle