在Spritekit中添加声音效果

Question

I'm making a Flappy Bird-type game, and I want to add a sound effect for when a coin is collected. This is what I have:

import SpriteKit
import AVFoundation

class GameScene: SKScene {

    var coinSound = NSURL(fileURLWithPath:NSBundle.mainBundle().pathForResource("Super Mario Bros.- Coin Sound Effect", ofType: "mp3")!)
    var audioPlayer = AVAudioPlayer()

Later in my didMoveToView:

audioPlayer = AVAudioPlayer(contentsOfURL: coinSound, error: nil)
audioPlayer.prepareToPlay()

For the second part (in my didMoveToView), the first line keeps showing an error:

Call can throw, but it is not marked with 'try' and the error is not handled

How do I fix this?

Answer 1

I know you already have marked an answer but if you re read this question or for future readers its easier to use SKActions to play a short 1 time sound.

AVFoundation is better used for background music.

eg

class GameScene: SKScene {

     // add as class property so sound is preloaded and always ready
     let coinSound = SKAction.playSoundFileNamed("NAMEOFSOUNDFILE", waitForCompletion: false)
}

and than when you need to play the sound simply say this

run(coinSound)

Hope this helps

Answer 2

 audioPlayer = AVAudioPlayer(contentsOfURL: coinSound, error: nil) 

This is no longer the way that errors are handled in Swift. You must use the do-try-catch syntax.

do {
    audioPlayer = try AVAudioPlayer(contentsOfURL: coinSound)
    audioPlayer.prepareToPlay()
}
catch let error {
    // handle error
}

Alternatively, if you don't care to write any error handling code, you can make your audioPlayer variable optional and write a failable try? :

audioPlayer = try? AVAudioPlayer(contentsOfURL: coinSound)
audioPlayer?.prepareToPlay()

This is more closely equivalent to the code you're attempting where you pass nil for the error parameter.

Or if crashing is the appropriate behavior when an error occurs, you could take this approach:

guard let audioPlayer = try? AVAudioPlayer(contentsOfURL: coinSound) else {
    fatalError("Failed to initialize the audio player with asset: \(coinSound)")
}
audioPlayer.prepareToPlay()
self.audioPlayer = audioPlayer

Answer 3

Swift 3.0+

For the above guard let example from @nhgrif, this Swift 3.0+ way of doing it:

var coinSound = NSURL(fileURLWithPath:Bundle.main.path(forResource: "Super Mario Bros.- Coin Sound Effect", ofType: "mp3")!)
var audioPlayer = AVAudioPlayer()

func playCoinSound(){
    guard let soundToPlay = try? AVAudioPlayer(contentsOf: coinSound as URL) else {
        fatalError("Failed to initialize the audio player with asset: \(coinSound)")
    }
    soundToPlay.prepareToPlay()

//  soundToPlay.play() // NO IDEA WHY THIS DOES NOT WORK!!!???

    self.audioPlayer = soundToPlay
    self.audioPlayer.play() // But this does work... please let me know why???
}

playCoinSound()