ios - 音频播放进度作为 Swift 中的 UISlider

Question

我看过一些关于在 Objective-C 中完成此操作的帖子，但我一直无法通过 Swift 完成同样的操作。

具体来说，我不知道如何在下面实现 addPeriodicTimeObserverForInterval。

var player : AVAudioPlayer! = nil

@IBAction func playAudio(sender: AnyObject) {
    playButton.selected = !(playButton.selected)
    if playButton.selected {
        let fileURL = NSURL(string: toPass)
        player = AVAudioPlayer(contentsOfURL: fileURL, error: nil)
        player.numberOfLoops = -1 // play indefinitely
        player.prepareToPlay()
        player.delegate = self
        player.play()
        startTime.text = "\(player.currentTime)"
        endTime.text = NSString(format: "%.1f", player.duration)
    } else {
        player.stop()
    }

如有任何帮助，我们将不胜感激。

Answer 1

感谢上面 Dare 的建议，我是这样完成的:

var updater : CADisplayLink! = nil

@IBAction func playAudio(sender: AnyObject) {
    playButton.selected = !(playButton.selected)
    if playButton.selected {
        updater = CADisplayLink(target: self, selector: Selector("trackAudio"))
        updater.frameInterval = 1
        updater.addToRunLoop(NSRunLoop.currentRunLoop(), forMode: NSRunLoopCommonModes)
        let fileURL = NSURL(string: toPass)
        player = AVAudioPlayer(contentsOfURL: fileURL, error: nil)
        player.numberOfLoops = -1 // play indefinitely
        player.prepareToPlay()
        player.delegate = self
        player.play()
        startTime.text = "\(player.currentTime)"
        theProgressBar.minimumValue = 0
        theProgressBar.maximumValue = 100 // Percentage
    } else {
        player.stop()
    }
}

func trackAudio() {
    var normalizedTime = Float(player.currentTime * 100.0 / player.duration)
    theProgressBar.value = normalizedTime
}

@IBAction func cancelClicked(sender: AnyObject) {
    player.stop()
    updater.invalidate()
    dismissViewControllerAnimated(true, completion: nil)

}