Asking for bluetooth permission for android 12 and above

[ahmetkocadogan]

Hello.

For Android 12 and above, apps have to ask bluetooth permission explicitly to be able to scan and print.

I didn't want to create a PR, i don't want to change your sample, but the code below can be added to help developers about asking permissions for bluetooth. You guys can add this in a suitable place in the demo if you want.

1st step:

Install Xamarin.Essentials to be able to use Permissions API, and make sure you are targeting at least Android 12.

2nd step: In shared project, create an interface like below

    public interface IPlatformHelpers
    {
        Task<PermissionStatus> CheckAndRequestBluetoothPermissions();
    }

3rd step: In Android project, create a class like below (Don't forget to change namespace , YourAppName to your app name.)

[assembly: Dependency(typeof(PlatformHelpers))]
namespace YourAppName.Droid
{
    public class PlatformHelpers : IPlatformHelpers
    {
        public async Task<PermissionStatus> CheckAndRequestBluetoothPermissions()
        {
            PermissionStatus status;
            if (Android.OS.Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.S)
            {
                status = await Permissions.CheckStatusAsync<BluetoothSPermission>();

                if (status == PermissionStatus.Granted)
                    return status;

                status = await Permissions.RequestAsync<BluetoothSPermission>();
            }
            else
            {
                status = await Permissions.CheckStatusAsync<Permissions.LocationWhenInUse>();

                if (status == PermissionStatus.Granted)
                    return status;

                status = await Permissions.RequestAsync<Permissions.LocationWhenInUse>();
            }
            return status;
        }
    }

    public class BluetoothSPermission : Xamarin.Essentials.Permissions.BasePlatformPermission
    {
        public override (string androidPermission, bool isRuntime)[] RequiredPermissions => new List<(string androidPermission, bool isRuntime)>
        {
            (Android.Manifest.Permission.BluetoothScan, true),
            (Android.Manifest.Permission.BluetoothConnect, true)
        }.ToArray();
    }
}

4th step:

Make sure you added this lines to your Android app manifest

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

5th step: Before scanning for bluetooth devices or printing, check and ask for the bluetooth permission

      var permissionResult = await DependencyService.Get<IPlatformHelpers>().CheckAndRequestBluetoothPermissions();
      if (permissionResult != PermissionStatus.Granted)
      {

      }

You can scan , connect and print after the app has the permission granted.

I just needed to do this modifications to my app because of the changes for bluetooth permissions for Android 12 and above.

Hope this helps people like me.