AVFoundation: prevent background music playing twice when returning to first screen - ios

Question

At the moment I have a home screen which plays background music using AVFoundation. If you click play the music stops (which is what I want).
If you move to the instructions screen the music continues (which I want), however when you click to return to home screen the background music continues (which I want), but a new track starts over the top.
In my mind what I ideally need is an if statement which prevents the music from restarting when I return to the home screen (if it is already playing). I have scoured the internet but I can't find any suggestions that will work.
This is the what I am currently working with,
class firstPageViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
backgroundMusic = self.setupAudioPlayerWithFile("background", type:"mp3")
backgroundMusic.volume = 0.3
backgroundMusic.numberOfLoops = -1
backgroundMusic.play()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
var backgroundMusic = AVAudioPlayer()
func setupAudioPlayerWithFile(file:NSString, type:NSString) -> AVAudioPlayer {
//1
var path = NSBundle.mainBundle().pathForResource(file as String, ofType: type as String)
var url = NSURL.fileURLWithPath(path!)
//2
var error: NSError?
//3
var audioPlayer:AVAudioPlayer?
audioPlayer = AVAudioPlayer(contentsOfURL: url, error: &error)
//4
return audioPlayer!
}
#IBAction func startGame(sender: UIButton) {
backgroundMusic.stop()
}
#IBAction func instructionsButton(sender: UIButton) {
}

Answer 1

var isMusicPlaying = 0
class firstPageViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
backgroundMusic = self.setupAudioPlayerWithFile("background", type:"mp3")
if isMusicPlaying == 0 {
backgroundMusic.volume = 0.3
backgroundMusic.numberOfLoops = -1
backgroundMusic.play()
}
if backgroundMusic.playing == true {
isMusicPlaying = 1
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
var backgroundMusic = AVAudioPlayer()
func setupAudioPlayerWithFile(file:NSString, type:NSString) -> AVAudioPlayer {
//1
var path = NSBundle.mainBundle().pathForResource(file as String, ofType: type as String)
var url = NSURL.fileURLWithPath(path!)
//2
var error: NSError?
//3
var audioPlayer:AVAudioPlayer?
audioPlayer = AVAudioPlayer(contentsOfURL: url, error: &error)
//4
return audioPlayer!
}