Play sound effect without latency - ios

Question

I am trying to make a little app to teach myself some swift and I'm having some problems figuring out how to get my app to function a certain way.
My app should be able to play an airhorn sound just like the way it sounds in this video...
https://www.youtube.com/watch?v=Ks5bzvT-D6I
But each time I tap the screen repeatedly there is a slight delay before the sound is played so it's not sounding like that at all.
import UIKit
import AVFoundation
class ViewController: UIViewController {
var audioPlayer = AVAudioPlayer()
override func viewDidLoad() {
super.viewDidLoad()
var hornSound = NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource("horn", ofType: "mp3")!)
AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback, error: nil)
AVAudioSession.sharedInstance().setActive(true, error: nil)
var error:NSError?
audioPlayer = AVAudioPlayer(contentsOfURL: hornSound, error: &error)
audioPlayer.prepareToPlay()
}
#IBAction func playSound(sender: UIButton) {
audioPlayer.pause()
audioPlayer.currentTime = 0
audioPlayer.play()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
I have also come across this thread about using spritekit
Creating and playing a sound in swift
And in trying that I got it to play the sound without the delay, but with sprite kit I can't stop the existing sound, so they just overlap which is not the effect I want.
Is there a work around to get this working the way it sounds in the video.

Answer 1

Apple recommends AVAudioPlayer for playback of audio data unless you require very low I/O latency.
So you might want to try another approach.
In one of my apps I play countdown sounds by creating a system sound ID from my wav file. Try this in your class:
import UIKit
import AudioToolbox
class ViewController: UIViewController {
var sound: SystemSoundID = 0
override func viewDidLoad() {
super.viewDidLoad()
var hornSound = NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource("horn", ofType: "mp3")!)
AudioServicesCreateSystemSoundID(hornSound!, &self.sound)
}
#IBAction func playSound(sender: UIButton) {
AudioServicesPlaySystemSound(self.sound)
}
...
}