How to Update player slider handle current value by AVAudioPlayer current time - ios

Question

Now I'm using the MSCircularSlider library as a Cocoapod. Its slider.value is slider.currentValue and when I try to do simple UISlider (try to equal slider.value to player.currentTime), it's working well, but when I try to do it in CircularSlider, the handle is not moving to the AVAudioPlayer.currentTime.
How to solve it?
Please, help me!
let player = AVAudioPlayer()
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
let cell = collectionView.cellForItem(at: indexPath) as! CustomCollectionCell
print("tapped")
guard let url = Bundle.main.url(forResource: songsData[indexPath.row].name, withExtension: "mp3") else { return }
do {
try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback, with: .mixWithOthers)
try AVAudioSession.sharedInstance().setActive(true)
player = try AVAudioPlayer(contentsOf: url, fileTypeHint: AVFileType.mp3.rawValue)
} catch let error {
print(error.localizedDescription)
}
player.prepareToPlay()
timerLabel.text = String(player.currentTime)
slider.alpha = 1
slider.maximumValue = Float(player.duration)
slider.currentValue = 0.0
Timer.scheduledTimer(timeInterval: 0.01, target: self, selector: #selector(updateTime), userInfo: nil, repeats: true)
player.play()
}
#objc func updateTime(_ timer: Timer) {
let currentTime = player.currentTime
var elapsedTime: TimeInterval = currentTime
let minutes = UInt8(elapsedTime / 60.0)
elapsedTime -= (TimeInterval(minutes) * 60)
let seconds = UInt8(elapsedTime)
elapsedTime -= TimeInterval(seconds)
let strMinutes = String(format: "%02d", minutes)
let strSeconds = String(format: "%02d", seconds)
timerLabel.text = "\(strMinutes):\(strSeconds)"
timer.invalidate()
self.slider.currentValue = Float(self.player.currentTime)
timer.invalidate()
}

Answer 1

Your updateTime(_:) code invalidates your timer. (Twice!) I would expect it to fire once after .01 seconds, then never again, and as a result you probably won't see a visible change in the slider value.
Get rid of the calls to timer.invalidate() except when the sound is finished playing.
I haven't used that particular framework before so I don't know for sure if it works as you're using it but a quick glance at the README file suggests that you are.
On another note, Timer objects are a little crude, and have a resolution of about 0.02 seconds at best, so a timer with an interval of 0.01 seconds isn't likely to fire that often. Also, the refresh rate on iOS device screens is 1/60th of a second, so there's no point in trying to update the screen more often than that.
If you really need smooth drawing that updates on every screen update you should look at using a CADisplayLink timer, but for something as simple as this a timer interval of 1/30 of a second or so should be fine.