Creating and playing a sound in swift

This is similar to some other answers, but perhaps a little more "Swifty":

// Load "mysoundname.wav"
if let soundURL = Bundle.main.url(forResource: "mysoundname", withExtension: "wav") {
    var mySound: SystemSoundID = 0
    AudioServicesCreateSystemSoundID(soundURL as CFURL, &mySound)
    // Play
    AudioServicesPlaySystemSound(mySound);
}

Note that this is a trivial example reproducing the effect of the code in the question. You'll need to make sure to import AudioToolbox, plus the general pattern for this kind of code would be to load your sounds when your app starts up, saving them in SystemSoundID instance variables somewhere, use them throughout your app, then call AudioServicesDisposeSystemSoundID when you're finished with them.

Here's a bit of code I've got added to FlappySwift that works:

import SpriteKit
import AVFoundation

class GameScene: SKScene {

    // Grab the path, make sure to add it to your project!
    var coinSound = NSURL(fileURLWithPath: Bundle.main.path(forResource: "coin", ofType: "wav")!)
    var audioPlayer = AVAudioPlayer()

    // Initial setup
    override func didMoveToView(view: SKView) {
        audioPlayer = AVAudioPlayer(contentsOfURL: coinSound, error: nil)
        audioPlayer.prepareToPlay()
    }

    // Trigger the sound effect when the player grabs the coin
    func didBeginContact(contact: SKPhysicsContact!) {
        audioPlayer.play()
    }

}

Handy Swift extension:

import AudioToolbox

extension SystemSoundID {
    static func playFileNamed(fileName: String, withExtenstion fileExtension: String) {
        var sound: SystemSoundID = 0
        if let soundURL = NSBundle.mainBundle().URLForResource(fileName, withExtension: fileExtension) {
            AudioServicesCreateSystemSoundID(soundURL, &sound)
            AudioServicesPlaySystemSound(sound)
        }
    }
}

Then, from anywhere in your app (remember to import AudioToolbox), you can call

SystemSoundID.playFileNamed("sound", withExtenstion: "mp3")

to play "sound.mp3"

This creates a SystemSoundID from a file called Cha-Ching.aiff.

import AudioToolbox

let chaChingSound: SystemSoundID = createChaChingSound()

class CashRegisterViewController: UIViewController {
    override func viewWillAppear(animated: Bool) {
        super.viewWillAppear(animated)
        AudioServicesPlaySystemSound(chaChingSound)
    }
}

func createChaChingSound() -> SystemSoundID {
    var soundID: SystemSoundID = 0
    let soundURL = CFBundleCopyResourceURL(CFBundleGetMainBundle(), "Cha-Ching", "aiff", nil)
    AudioServicesCreateSystemSoundID(soundURL, &soundID)
    CFRelease(soundURL)
    return soundID
}