Can I keep Bluetooth always on using MvvmCross

Understanding the Limitations

- No Direct API: There is no direct API in Android that allows you to keep Bluetooth always on programmatically. Bluetooth is typically turned off by the system or user actions[1].
- MvvmCross and Bluetooth LE: MvvmCross provides a Bluetooth Low Energy (BLE) plugin that allows you to access Bluetooth functionality, but it does not inherently keep Bluetooth always on. It is designed for BLE operations rather than managing the Bluetooth state[2][4].

Workaround: Monitoring and Re-enabling Bluetooth

To keep Bluetooth active, you can use a `BroadcastReceiver` to monitor Bluetooth state changes. When the Bluetooth state changes to "off," you can prompt the user to turn it back on or handle it programmatically if possible.

1. Define Permissions: Ensure your app has the necessary permissions to access Bluetooth. You will need `BLUETOOTH`, `BLUETOOTH_ADMIN`, and possibly others depending on your specific use case.

2. Create a BroadcastReceiver:

csharp
   [BroadcastReceiver(Enabled = true, Exported = true)]
   [IntentFilter(new[] { BluetoothAdapter.ActionStateChanged })]
   public class BluetoothStateReceiver : BroadcastReceiver
   {
       public override void OnReceive(Context context, Intent intent)
       {
           string action = intent.Action;
           if (BluetoothAdapter.ActionStateChanged.Equals(action))
           {
               int state = intent.GetIntExtra(BluetoothAdapter.ExtraState, BluetoothAdapter.ERROR);
               if (state == BluetoothAdapter.STATE_OFF)
               {
                   // Handle Bluetooth being turned off here.
                   // You might prompt the user to turn it back on.
               }
           }
       }
   }
   

3. Register the BroadcastReceiver: Register this receiver in your app's startup code, typically in the `MainActivity` or `Application` class.

4. Prompt User or Handle Programmatically: When Bluetooth is turned off, you can either prompt the user to turn it back on or attempt to handle it programmatically if your app has the necessary permissions and capabilities.

MvvmCross BLE Plugin Usage

While the MvvmCross BLE plugin does not keep Bluetooth always on, you can use it to manage BLE connections and monitor Bluetooth state changes. Here’s how you might use it:

csharp
var ble = Mvx.Resolve();
var adapter = Mvx.Resolve();

// Monitor Bluetooth state changes
ble.StateChanged += (s, e) =>
{
    Debug.WriteLine($"The Bluetooth state changed to {e.NewState}");
    if (e.NewState == BluetoothState.Off)
    {
        // Handle Bluetooth being turned off here.
    }
};

Conclusion

While there is no direct way to keep Bluetooth always on using MvvmCross or any other framework in Android, you can implement a workaround by monitoring Bluetooth state changes and prompting the user to re-enable it when necessary. This approach requires careful handling of permissions and user interactions to ensure a seamless experience.