Swift - 按下按钮(完成处理程序问题)

Question

我希望用户按下一个按钮，它会改变背景颜色(黄色)，播放 WAV 并在完成 WAV 后按钮恢复到其原始颜色(红色)。所以在声音周围有一个完成处理程序。尝试了以下代码的各种组合，但 WAV 播放并且按钮似乎没有改变颜色。

这是错误的方法还是我做错了什么？不想在颜色变化周围放置完成处理程序，因为我认为这太过分了。

非常感谢。

typealias CompletionHandler = (success:Bool) -> Void

@IBAction func fireButton(sender: AnyObject) {
    playLaser( { (success)-> Void in
        if success {
            self.shots -= 1
            self.labelShotsLeft.text = String(self.shots)
        } else {

        }
    })
}

 func playLaser(completionHandler: CompletionHandler) {
     fireButton.layer.backgroundColor = UIColor.yellowColor().CGColor
     let url = NSBundle.mainBundle().URLForResource("laser", withExtension: "wav")!
    do {
        player = try AVAudioPlayer(contentsOfURL: url)
        guard let player = player else { return }
        player.prepareToPlay()
        player.play()
        } catch let error as NSError {
            print(error.description)
    }
    self.fireButton.layer.backgroundColor = UIColor.redColor().CGColor
    completionHandler(success: true)
}

Answer 1

要检测AVAudioPlayer播放完毕，需要使用AVAudioPlayerDelegate。

你可能需要这样写:

func playLaser(completionHandler: CompletionHandler) {
    fireButton.layer.backgroundColor = UIColor.yellowColor().CGColor
    let url = NSBundle.mainBundle().URLForResource("laser", withExtension: "wav")!
    do {
        player = try AVAudioPlayer(contentsOfURL: url)
        guard let player = player else { return }
        player.delegate = self //<- Sorry, this was missing in my first post
        player.play()
    } catch let error as NSError {
        print(error.description)
    }
    audioPlayerCompletionHandler = completionHandler
}

var audioPlayerCompletionHandler: CompletionHandler?
func audioPlayerDidFinishPlaying(player: AVAudioPlayer, successfully flag: Bool) {
    self.fireButton.layer.backgroundColor = UIColor.redColor().CGColor
    audioPlayerCompletionHandler?(success: true)
}

(您需要将对 AVAudioPlayerDelegate 的一致性添加到 ViewController 的声明 header 中。)