音频播放在Swift中作为UISlider进行 [英] Audio playback progress as UISlider in Swift

问题描述

我已经看过一些关于在Objective-C中完成此事的帖子，但我一直无法通过Swift做同样的事情。

I've seen some posts about accomplishing this in Objective-C but I've been unable to do the same via Swift.

具体来说，我无法弄清楚如何在下面实现 addPeriodicTimeObserverForInterval 。

Specifically, I can't figure out how to implement addPeriodicTimeObserverForInterval in the below.

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()
    }

任何帮助都将不胜感激。

Any assistance would be appreciated.

推荐答案

感谢上面Dare的建议，以下是我如何做到这一点：

Thanks to the suggestion of Dare above, here's how I accomplished this:

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)

}

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