Swift: Load a Wav sound using AVFoundation

I sometimes need to dynamically load a .wav file.  Here's how I do it using AVFoundation.

func changeSound(_ song:(path: String, format: String)){
        var err:NSError?
        let track = Bundle.main.path(forResource: song.path, ofType: song.format)!
        let u = URL(fileURLWithPath: track)
        do {
            audioPlayer = try AVAudioPlayer(contentsOf: u)
        } catch let error as NSError {
            err = error
            audioPlayer = nil
        }
        if let error = err {
            print("audioPlayer Err: \(error.localizedDescription)")
        } else {
            audioPlayer?.prepareToPlay()
        }
        if let player = audioPlayer {
            player.play()
        }

    }