I'm trying to record video, with audio input coming from a connected Bluetooth headset. However I haven't been able to get an AVCaptureDevice that represents the headset, so I can't add it to my AVCaptureSession.I tried to find it using a discovery session, but it never finds the headset-- only the built in microphone. That may not be surprising since I'm asking for .builtInMicrophone, but the enumeration has no members for external audio inputs. I tried leaving the device type array empty but that finds no devices.let discoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInMicrophone], mediaType: AVMediaType.audio, position: .unspecified) print("Found \(discoverySession.devices.count) devices") for device in discoverySession.devices { print("Device: \(device)") }After doing some searching I tried setting up the AVAudioSession to specifically allow Bluetooth. However this has had no effect on the above.private let session = AVCaptureSession() // later... session.usesApplicationAudioSession = true session.automaticallyConfiguresApplicationAudioSession = false do { try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayAndRecord, with: [.allowBluetooth]) try AVAudioSession.sharedInstance().setActive(true) } catch { print("Error messing with audio session: \(error)") }For completeness I also tried the deprecated AVCaptureDevice.devices() method, but it doesn't find the Bluetooth headset either.I know that the headset is available because AVAudioSession can see it. However I haven't been able to get from the availableInputs array to something I can use in an AVCaptureSession. The following code finds the headset, but what would I do with the result? It's not an AVCaptureDevice nor can I construct one from the entries in the array. Setting the "preferred" input doesn't have any effect that I know how to use.if let availableInputs = AVAudioSession.sharedInstance().availableInputs { print("Found \(availableInputs.count) inputs") for input in availableInputs { print("Input: \(input)") if input.portType == AVAudioSessionPortBluetoothHFP { print("Setting preferred input") do { try AVAudioSession.sharedInstance().setPreferredInput(input) } catch { print("Error setting preferred input: \(error)") } } } }Given that the Bluetooth headset is connected and available, how do I set it as the audio input for my capture session?