Comparing AVAudioSession.Location & AVAudioSession.Orientation in Swift

AVAudioSession.Orientation has no constants defined in Swift. If one is given an AVAudioSession.Location value, how do we compare it against a value of type AVAudioSession.Orientation?

Specifically, I have found the following works, but I am not sure it's a reliable and correct way to compare and if it will work always on all iOS versions.

    var preferredDataSource:AVAudioSessionDataSourceDescription?
    let preferredMicrophoneLocation = AVAudioSession.Location.orientationFront

     if let dataSources = builtinMicPort.dataSources {
           for source in dataSources
               {
                if source.orientation?.rawValue == preferredMicrophoneLocation.rawValue 
                            preferredDataSource = source
                            break
                        }
                    } // end data source iteration
                }
     }