allocate allocate - 6 months ago 127
iOS Question

Audio playback progress as UISlider in Swift

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

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()
}


Any assistance would be appreciated.

Answer

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)

}