public Adapter()
{
var appContext = Android.App.Application.Context;
_manager = (BluetoothManager)appContext.GetSystemService("bluetooth");
_adapter = _manager.Adapter;
_callback = new GattCallback();
_callback.DeviceConnected += BluetoothGatt_DeviceConnected;
_callback.DeviceDisconnected += BluetoothGatt_DeviceDisconnected;
ConnectedDevices = new List<IDevice>();
}