MAUI Bluetooth Permission Declaration (for Android)

BluetoothPermissions.Android.cs

// IMPORTANT: Put this file in `Platforms/Android/` directory.
using Microsoft.Maui.ApplicationModel;
using System.Collections.Generic;

/// <summary>
///		MAUI Bluetooth Permission Decleration (for Android).
/// </summary>
/// <remarks>
///		IMPORTANT: Put this file in `Platforms/Android/` directory.
/// </remarks>
public partial class BluetoothPermissions : Permissions.BasePlatformPermission
{
	private readonly bool _scan;
	private readonly bool _advertise;
	private readonly bool _connect;
	private readonly bool _bluetoothLocation;

	public BluetoothPermissions()
		: this(true, false, true, false)
	{
	}

	/// <summary>
	/// 
	/// </summary>
	/// <param name="scan">Needed only if your app looks for Bluetooth devices.
	/// If your app doesn't use Bluetooth scan results to derive physical location, you can make a strong assertion that your app never uses the Bluetooth permissions to derive physical location. 
	/// Add the `android:usesPermissionFlags` attribute to your BLUETOOTH_SCAN permission declaration, and set this attribute's value to `neverForLocation`.
	/// </param>
	/// <param name="advertise">Needed only if your app makes the device discoverable to Bluetooth devices.</param>
	/// <param name="connect">Needed only if your app communicates with already-paired Bluetooth devices.</param>
	/// <param name="bluetoothLocation">Needed only if your app uses Bluetooth scan results to derive physical location.</param>
	/// <remarks>
	///  https://developer.android.com/guide/topics/connectivity/bluetooth/permissions
	/// </remarks>
	public BluetoothPermissions(bool scan = true, bool advertise = true, bool connect = true, bool bluetoothLocation = true)
	{
		_scan = scan;
		_advertise = advertise;
		_connect = connect;
		_bluetoothLocation = bluetoothLocation;
	}

	private (string androidPermission, bool isRuntime)[] _requiredPermissions;

	public override (string androidPermission, bool isRuntime)[] RequiredPermissions
	{
		get
		{
			if (_requiredPermissions != null)
				return _requiredPermissions;

			var result = new List<(string androidPermission, bool isRuntime)>();

			var sdk = (int)Android.OS.Build.VERSION.SdkInt;
			if (sdk >= 31)
			{
				// If your app targets Android 12 (API level 31) or higher, declare the following permissions in your app's manifest file:

				if (_scan)
					result.Add((global::Android.Manifest.Permission.BluetoothScan, true));

				if (_advertise)
					result.Add((global::Android.Manifest.Permission.BluetoothAdvertise, true));

				if (_connect)
					result.Add((global::Android.Manifest.Permission.BluetoothConnect, true));

				if (_bluetoothLocation)
					result.Add((global::Android.Manifest.Permission.AccessFineLocation, true));
			}
			else
			{
				// If your app targets Android 11 (API level 30) or lower, declare the following permissions in your app's manifest file:

				result.Add((global::Android.Manifest.Permission.Bluetooth, true));

				if (sdk >= 29)
				{
					result.Add((global::Android.Manifest.Permission.AccessFineLocation, true));
				}
				else
				{
					// If your app targets Android 9 (API level 28) or lower, you can declare the ACCESS_COARSE_LOCATION permission instead of the ACCESS_FINE_LOCATION permission.

					result.Add((global::Android.Manifest.Permission.AccessCoarseLocation, true));
				}

				if (_scan || _connect || _advertise)
				{
					result.Add((global::Android.Manifest.Permission.BluetoothAdmin, true));

					if (sdk >= 29)
					{
						// If your app supports a service and can run on Android 10 (API level 29) or Android 11, you must also declare the ACCESS_BACKGROUND_LOCATION permission to discover Bluetooth devices. 

						result.Add((global::Android.Manifest.Permission.AccessBackgroundLocation, true));
					}
				}
			}
			_requiredPermissions = result.ToArray();

			return _requiredPermissions;
		}
	}
}

BluetoothPermissions.cs

	/// <summary>
	/// IMPORTANT: Put this file in root of Application
	/// </summary>
	public partial class BluetoothPermissions : Permissions.BasePlatformPermission
	{
	}

BluetoothPermissions.Helper.cs

// How to use MAUI Bluetooth LE permissions

private async Task<bool> CheckBluetoothStatus()
{
	try
	{
		var requestStatus = await new BluetoothPermissions().CheckStatusAsync();
		return requestStatus == PermissionStatus.Granted;
	}
	catch (Exception ex)
	{
		// logger.LogError(ex);
		return false;
	}
}

public async Task<bool> RequestBluetoothAccess()
{
	try
	{
		var requestStatus = await new BluetoothPermissions().RequestAsync();
		return requestStatus == PermissionStatus.Granted;
	}
	catch (Exception ex)
	{
		// logger.LogError(ex);
		return false;
	}
}

That's fantastic, thankyou so much. I put a question on stackoverflow about this, so I'll put a link to the github question and here. I guess I can easily add my own prompt popup screen.

I cant tell you how delighted I am about this and I've even managed to get plugin.BLE scanning. With the knowledge gained from your examples I can improve the code below, but at least it works. Long way to go, but now I can make progress. If you have a donate page let me buy you a beer (or a litre of petrol) :)

using Plugin.BLE;
...

    StartScanning();
    static async void  StartScanning()
    {
      var ble = CrossBluetoothLE.Current;
      var adapter = CrossBluetoothLE.Current.Adapter;
      var state = ble.State;

      adapter.DeviceDiscovered += (s, a) => Console.WriteLine(a.Device);
      await adapter.StartScanningForDevicesAsync();
    }

I'm glad this was helpful. All good :)
Thanks for letting me know about plugin.BLE

Have you the same example for iOS please ?

Is there a VS solution with all this together so I can conceptualize it? Thanks in advance!

Correct me if im wrong but, it appears to me neither Bluetooth nor BluetoothAdmin are runtime permissions, and thus do not need the runtime parameter to be true.
From what i see in the source code, the only use to even include them in this RequiredPermissions override is to let MAUI ensure they are part of the manifest, but marking them as runtime is misleading/confusing.

Also it seems to me that since CheckStatus/Request permissions only returns a single over all PermissionStatus, than adding both the Bluetooth specific as well as Location specific permissions, to the same RequiredPermissions enumeration, will not allow you to differentiate which permissions if any had not been granted, rather just that something wasn't.
So if you need to know which may have been denied, you wont unless they are requested separately.
For after the permission is denied twice, additional request will not be granted, and arguably you might want to know what exactly was denied to help guide the user to allow the permission manually.

Shoutout to @salarcode , this was of amazing help saved many hours of banging my head against a wall

Hello and thank you for this code.
However, I don't understand the purpose of the BluetoothPermissions class at the root of Application.
How do you make the link between BluetoothPermissions at the root of Application and BluetoothPermissions in Platforms.Android ?
I have the impression that my programme doesn't pass into BluetoothPermissions in Plateforms.Android...

Hi, I'm sorry it's been a long time since I worked on this code that I cannot remember anything about it. Have a look at the stackoverflow post, it may help. Also Maui has had some major updates since I worked with it that things may have changed. I hope you figure it out because it was a right mess.
Gordon

Hello and thank you for this code. However, I don't understand the purpose of the BluetoothPermissions class at the root of Application. How do you make the link between BluetoothPermissions at the root of Application and BluetoothPermissions in Platforms.Android ? I have the impression that my programme doesn't pass into BluetoothPermissions in Plateforms.Android...

@ALEXJNX
I believe you need to make clear what you mean by root of Application I dont think it is proper terminology so it cant clearly explain what you are trying to say.
Anyway MAUI is cross platform, so some of this code is abstracted and some is platform specific, I advise you get familiar with that first which will make it more easy to understand here.

Hello and thank you for this code. However, I don't understand the purpose of the BluetoothPermissions class at the root of Application. How do you make the link between BluetoothPermissions at the root of Application and BluetoothPermissions in Platforms.Android ? I have the impression that my programme doesn't pass into BluetoothPermissions in Plateforms.Android...

Ok, I Find answer here : https://learn.microsoft.com/en-us/dotnet/maui/platform-integration/invoke-platform-code?view=net-maui-8.0#partial-classes-and-methods