iOS， swift : play background music and sound effects without delay

Question

我正在尝试在不使用 SpriteKit 的情况下在 iOS 中创建游戏。我一直致力于让音效及时播放。我一直在使用我在网上找到的以下代码，并且背景音乐播放得很好。但是，当我使用“playSoundEffect”方法第一次播放正常，但随后开始落后并变得不同步。我猜发生这种情况是因为它每次都会初始化一个 AVAudioPlayer 。有人知道如何在播放背景音乐的同​​时及时播放音效吗？谢谢!

import AVFoundation

public class SKTAudio: NSObject, AVAudioPlayerDelegate {
public var backgroundMusicPlayer: AVAudioPlayer?
public var soundEffectPlayer: AVAudioPlayer?

private var mainLoopFileName:String! {

    let randomSong = Int(arc4random_uniform(3))

    switch randomSong {
    //case 0: return "Test.mp3"
    //case 1: return "Test2.mp3"
    case 0: return "SneakySnitch.mp3"
    case 1: return "FasterDoesIt.mp3"
    case 2: return "MonkeysSpinningMonkeys.mp3"
    default:
        break
    }

    return "SneakySnitch.mp3"
}

public class func sharedInstance() -> SKTAudio {
    return SKTAudioInstance
}

public func playBackgroundMusic() {
    let filename = mainLoopFileName
    let url = NSBundle.mainBundle().URLForResource(filename, withExtension: nil)
    if (url == nil) {
        println("Could not find file: \(filename)")
        return
    }

    var error: NSError? = nil
    backgroundMusicPlayer = AVAudioPlayer(contentsOfURL: url, error: &error)
    if let player = backgroundMusicPlayer {
        player.numberOfLoops = 0
        player.delegate = self
        player.prepareToPlay()
        player.play()
    } else {
        println("Could not create audio player: \(error!)")
    }
}

public func pauseBackgroundMusic() {
    if let player = backgroundMusicPlayer {
        if player.playing {
            player.pause()
        }
    }
}

public func resumeBackgroundMusic() {
    if let player = backgroundMusicPlayer {
        if !player.playing {
            player.play()
        }
    }
}

public func playSoundEffect(filename: String) {
    let url = NSBundle.mainBundle().URLForResource(filename, withExtension: nil)
    if (url == nil) {
        println("Could not find file: \(filename)")
        return
    }

    var error: NSError? = nil
    soundEffectPlayer = AVAudioPlayer(contentsOfURL: url, error: &error)
    if let player = soundEffectPlayer {
        player.numberOfLoops = 0
        player.prepareToPlay()
        player.play()
    } else {
        println("Could not create audio player: \(error!)")
    }
}

// MARK: AVAudioPlayerDelegate
public func audioPlayerDidFinishPlaying(player: AVAudioPlayer!, successfully flag: Bool) {
    println("finished playing \(flag)")

    delay(5.0, {
        self.playBackgroundMusic()
    })
}

public func audioPlayerDecodeErrorDidOccur(player: AVAudioPlayer!, error: NSError!) {
    println("\(error.localizedDescription)")
}

}

Answer 1

您可以使用 AVPlayer 来播放您的声音文件。保留一个播放器，但当您需要播放新声音时，将其 AVPlayerItem 更改为一个新项目。这可能比每次都重新创建播放器更快。

虽然 AVAudioPlayer/AVPlayer 是最简单的选项，但它不会在播放音频文件时为您提供最短的延迟或完美的同步。您应该查看 Core Audio 中的音频队列或音频单元以获得更准确的声音播放。