Play a sound with AVAudioPlayer

playSoundWithAVAudioPlayer

func playSoundWithAVAudioPlayer() {
        var alertSound = NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource("alert", ofType: "mp3"))
        
        var error:NSError?
        
        if !AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback, error: &error) {
            if let err = error {
                println("could not set session category: \(err.localizedDescription)")
            }
        }

        if !AVAudioSession.sharedInstance().setActive(true, error: &error) {
            if let err = error {
                println("could not make session active: \(err.localizedDescription)")
            }
        }
        
        var audioPlayer = AVAudioPlayer(contentsOfURL: alertSound, error: &error)
        if let err = error {
            println("could not create player: \(err.localizedDescription)")
        }
        audioPlayer.prepareToPlay()
        audioPlayer.play()

    }