Singleton AudioManager written in Swift

AudioManager

//
//  AudioManager.swift
//  blocks
//
//  Created by Ian Richardson on 8/22/14.
//  Copyright (c) 2014 3 Screen Apps. All rights reserved.
//

import Foundation
import AVFoundation

class AudioManager {
    
    var audioPlayer = AVAudioPlayer()

    class var sharedInstance: AudioManager {
        struct Static {
            static var instance: AudioManager?
            static var token: dispatch_once_t = 0
        }
        dispatch_once(&Static.token) {
            Static.instance = AudioManager()
        }
        return Static.instance!
    }
    
    func playAudio(fileName: String, fileType: String, loop: Int){
        var url = NSURL.fileURLWithPath(NSBundle.mainBundle().pathForResource(fileName, ofType: fileType)!)
        audioPlayer = AVAudioPlayer(contentsOfURL: url, error: nil)
        audioPlayer.play()
        audioPlayer.numberOfLoops = loop
    }
    
    func stopAudio(){
        audioPlayer.stop()
    }
}

I utilize the AudioManager Class in a view controller like this:

class VC: UIViewController {
        override func viewDidLoad() {
        super.viewDidLoad()
        let player = AudioManager.sharedInstance
        player.playAudio("audioname", fileType: "mp3")

    }
}

Then I dismiss the current view controller and re-enter the view controller, the audio restart and play from the beginning.
I want to know how to make the audio continue playing without restart.
Thank you.

In the "PlayAudio" function just check which audio is playing, and if it's
the same don't restart it.