Creating sound effects for bouncing ball in SpriteKit - swift

Question

My Swift game uses SpriteKit and SKPhysics to animate a small red ball that frequently collides with other physicsBodys over the course of the game. I want to create an natural sounding bounce sound effect whenever the ball collides. I currently have a rather disorderly method for doing this, and there's a significant lag noticeable while employing it that disappears when I disable sounds:
var bounceSoundPlayers = [AVAudioPlayer!]()
func buildBounceSound() {
let path = Bundle.main.path(forResource: "Bounce.mp3", ofType:nil)!
let url = URL(fileURLWithPath: path)
for _ in 0...2 {
do {
let sound = try AVAudioPlayer(contentsOf: url)
sound.prepareToPlay()
bounceSoundPlayers.append(sound)
} catch {
fatalError("couldn't load music file")
}
}
}
This creates three AVAudioPlayers with sound "Bounce.mp3" and runs the prepareToPlay() method on them. Then it stores them in an array called bounceSoundPlayers so I can use them later. Then I have a didBeginContact method that is called whenever anything collides with anything:
func didBegin(_ contact: SKPhysicsContact) {
if contact.collisionImpulse > 0.45 && defaults.bool(forKey: "SFX") {
if ((contact.bodyA.node!.name == "ball" && contact.bodyB.node!.name == "permeable platform") ||
(contact.bodyB.node!.name == "ball" && contact.bodyA.node!.name == "permeable platform") ||
(contact.bodyA.node!.name == "ball" && contact.bodyB.node!.name == "ring") ||
(contact.bodyB.node!.name == "ball" && contact.bodyA.node!.name == "ring"))
&&
ball.collidingWithPermeable {
playBounceSound(contact.collisionImpulse/8<=1 ? contact.collisionImpulse/8 : 1)
}
if (contact.bodyA.node!.name == "ball" && contact.bodyB.node!.name == "impermeable platform") ||
(contact.bodyB.node!.name == "ball" && contact.bodyA.node!.name == "impermeable platform") ||
(contact.bodyA.node!.name == "ball" && contact.bodyB.node!.name == "wall") ||
(contact.bodyB.node!.name == "ball" && contact.bodyA.node!.name == "wall") {
playBounceSound(contact.collisionImpulse/5<=1 ? contact.collisionImpulse/5 : 1)
}
}
}
Basically what this method does is it checks each collision, and if the ball collides with the right kind of platform or wall, it calls the method playBounceSound(volume: CGFloat) with a volume proportional to the force of the collision. So if the ball collides with a platform lightly, the volume is quieter than if it's a really strong collision. Here's the playBounceSound method:
var bouncePlayerIndex = Int(0)
func playBounceSound(_ volume: CGFloat) {
let previousIndex = bouncePlayerIndex - 1 >= 0 ? bouncePlayerIndex - 1 : 2
if bounceSoundPlayer[previousIndex].isPlaying {
if bounceSoundPlayer[previousIndex].currentTime > 0.1 {
bounceSoundPlayer[bouncePlayerIndex].volume = Float(volume)
bounceSoundPlayer[bouncePlayerIndex].play()
}
}
else {
bounceSoundPlayer[bouncePlayerIndex].volume = Float(volume)
bounceSoundPlayer[bouncePlayerIndex].play()
}
bouncePlayerIndex += 1
if bouncePlayerIndex > 2 {bouncePlayerIndex = 0}
}
Basically what this method does is it cycles through the three AVAudioPlayers we created earlier by using an index integer. Every time it's called, it tells the bounceSoundPlayer at bouncePlayerIndex to play() at the given volume. Then it increments bouncePlayerIndex so that next time it's called, it uses a different AVAudioPlayer. If bouncePlayerIndex > 2, it goes back to 0. Using three AVAudioPlayers allows me to play multiple bounces simultaneous — i.e. a bounce sound can begin before the last one ended, such as when the ball lands on a platform and bounces high, then lower and lower and more frequently, until it stops bouncing.
I'm sure there's a better way of doing this than with an array of AVAudioPlayers. Please help.

Answer 1

Swift 3
This is the best way I have found to play sounds. They can overlap and you can play as many as you want at the same time. Fast and simple.
1.) Make sure you import the framework
import AVFoundation
2.) Create the function
// my sound file is named shatter.mp3
func shatterSound() {
if let soundURL = Bundle.main.url(forResource: "shatter", withExtension: "mp3") {
var mySound: SystemSoundID = 0
AudioServicesCreateSystemSoundID(soundURL as CFURL, &mySound)
AudioServicesPlaySystemSound(mySound);
}
}
3.) Call the function where you need it with
shatterSound()