ios Swift 中作为 UISlider 的音频播放进度

Audio playback progress as UISlider in Swift

提问by allocate

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

我看过一些关于在 Objective-C 中完成这个的帖子，但我一直无法通过 Swift 做到这一点。

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

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

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()
    }

Any assistance would be appreciated.

任何援助将不胜感激。

回答by allocate

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

感谢上面 Dare 的建议，以下是我完成此操作的方法：

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)

}

回答by Dare

Just to elaborate on my previous comment, this is how I implemented it and it seems to work pretty well. Any Swift corrections are more than welcome, I'm still an Obj-C guy for now.

只是为了详细说明我之前的评论，这就是我实现它的方式，它似乎工作得很好。任何 Swift 更正都非常受欢迎，我现在仍然是一个 Obj-C 人。

@IBAction func playAudio(sender: AnyObject) {

    var playing = false

    if let currentPlayer = player {
        playing = player.playing;
    }else{
        return;
    }

    if !playing {
        let filePath = NSBundle.mainBundle().pathForResource("3e6129f2-8d6d-4cf4-a5ec-1b51b6c8e18b", ofType: "wav")
        if let path = filePath{
            let fileURL = NSURL(string: path)
            player = AVAudioPlayer(contentsOfURL: fileURL, error: nil)
            player.numberOfLoops = -1 // play indefinitely
            player.prepareToPlay()
            player.delegate = self
            player.play()

            displayLink = CADisplayLink(target: self, selector: ("updateSliderProgress"))
            displayLink.addToRunLoop(NSRunLoop.currentRunLoop(), forMode: NSDefaultRunLoopMode!)
        }

    } else {
        player.stop()
        displayLink.invalidate()
    }
}

func updateSliderProgress(){
    var progress = player.currentTime / player.duration
    timeSlider.setValue(Float(progress), animated: false)
}

*I set time slider's range between 0 and 1 on a storyboard

*我在情节提要上将时间滑块的范围设置在 0 和 1 之间

回答by Delabi

Specifically for Swift I was able to handle it like this:

特别是对于 Swift，我能够像这样处理它：

1. I set the maximum value of the scrubSliderto the duration of the music file(.mp3) that was loaded in this method

   override func viewDidLoad() {
       super.viewDidLoad()
   
       do {
   
           try player = AVAudioPlayer(contentsOfURL: NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource("bach", ofType: "mp3")!))
   
           scrubSlider.maximumValue = Float(player.duration)
   
       } catch {
           //Error
       } 
   
       _ = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: #selector(ViewController.updateScrubSlider), userInfo: nil, repeats: true)
   
   }
   

2. I player was set to play the music at the time set by the value of the scrubber.

   @IBAction func scrub(sender: AnyObject) {
   
       player.currentTime = NSTimeInterval(scrubSlider.value)
   
   }
   

1. 我将 的最大值设置为scrubSlider在此方法中加载的音乐文件 (.mp3) 的持续时间

   override func viewDidLoad() {
       super.viewDidLoad()
   
       do {
   
           try player = AVAudioPlayer(contentsOfURL: NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource("bach", ofType: "mp3")!))
   
           scrubSlider.maximumValue = Float(player.duration)
   
       } catch {
           //Error
       } 
   
       _ = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: #selector(ViewController.updateScrubSlider), userInfo: nil, repeats: true)
   
   }
   

2. 我的播放器被设置为在洗涤器的值设置的时间播放音乐。

   @IBAction func scrub(sender: AnyObject) {
   
       player.currentTime = NSTimeInterval(scrubSlider.value)
   
   }
   

回答by BlackVoid

Syntax has now changed in Swift 4:

Swift 4 中的语法现已更改：

updater = CADisplayLink(target: self, selector: #selector(self.trackAudio))
updater.preferredFramesPerSecond = 1
updater.add(to: RunLoop.current, forMode: RunLoopMode.commonModes)

And the function (I have previously set the progressSlider.maxValue to player.duration):

和功能（我之前已将progressSlider.maxValue 设置为player.duration）：

@objc func trackAudio() {
    progressSlider.value = Float(player!.currentTime)
 }