How to prevent periodicTimeObserver updating the progressBar while user drags the slider manually? - swift

Question

I have a periodicTimeObserver and it updates the elapsed and remaining timeLabels in the way I want, but the slider is jumping. How to prevent periodicTimeObserver updating the UISlider while user drags the slider manually?
This is my UISlider
private lazy var progressBar: UISlider = {
let v = UISlider()
v.translatesAutoresizingMaskIntoConstraints = false
//v.minimumTrackTintColor = UIColor(named: "PlayerColors")
v.isContinuous = false
return v
}()
Periodic time observer which updates the UISlider and the elapsed and remaining time labels.
player = AVPlayer(playerItem: playerItem)
player!.addPeriodicTimeObserver(forInterval: CMTimeMakeWithSeconds(1, preferredTimescale: 1), queue: DispatchQueue.main) { (CMTime) -> Void in
if self.player!.currentItem?.status == .readyToPlay {
let currentTime : Float64 = CMTimeGetSeconds(self.player!.currentTime());
let totalTime : Float64 = CMTimeGetSeconds(self.player!.currentItem!.duration);
self.progressBar.value = Float(currentTime)
self.progressBar.minimumValue = 0
self.progressBar.maximumValue = Float(totalTime)
self.elapsedTimeLabel.text = self.stringFromTimeInterval(interval: currentTime)
self.remainingTimeLabel.text = self.stringFromTimeIntervalRemaining(interval: totalTime - currentTime)
The function that should seek to a point of the audio and update the time labels.
#objc func progressScrubbed(_ :UISlider) {
let seconds : Int64 = Int64(self.progressBar.value)
let targetTime:CMTime = CMTimeMake(value: seconds, timescale: 1)
player!.seek(to: targetTime)
if player!.rate == 0
{
play()
}
}

Answer 1

You need to know if user is interacting with a slider in order to ignore PeriodicTimeObserver. Moreover you need to reset PeriodicTimeObserver on each seek. So let's create a custom UISlider and override a one method:
class MySlider: UISlider {
var onTouchesBegan: (() -> ())?
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
super.touchesBegan(touches, with: event)
onTouchesBegan?()
}
}
Now you can create a parameter which will track if slider is touched or not and set it in closures of MySlider:
private var isTouchingSlider: Bool = false
private lazy var progressBar: MySlider = {
let v = MySlider()
v.translatesAutoresizingMaskIntoConstraints = false
v.isContinuous = false
v.onTouchesBegan = { [weak self] in
self?.isTouchingSlider = true
}
return v
}()
And your periodic observer methods would look like this:
var periodicObserverToken: Any?
func addPeriodicTimeObserver() {
let interval = CMTime(
seconds: 1,
preferredTimescale: CMTimeScale(NSEC_PER_SEC)
)
periodicObserverToken = player?.addPeriodicTimeObserver(forInterval: interval, queue: .main) { [weak self] _ in
guard let `self` = self, let player = self.player, player.currentItem?.status == .readyToPlay, let currentItem = self.player.currentItem, !self.isTouchingSlider else { return }
let currentTime : Float64 = CMTimeGetSeconds(player.currentTime());
let totalTime : Float64 = CMTimeGetSeconds(currentItem.duration);
self.progressBar.value = Float(currentTime)
self.progressBar.minimumValue = 0
self.progressBar.maximumValue = Float(totalTime)
}
}
private func removePeriodicTimeObserver() {
guard let periodicObserverToken = periodicObserverToken else { return }
player?.removeTimeObserver(periodicObserverToken)
self.playerPeriodicTimeObserver = nil
}
You need to make all the necessary updates when slider is updated:
#objc func progressScrubbed(_ :UISlider) {
let seconds : Int64 = Int64(self.progressBar.value)
let targetTime:CMTime = CMTimeMake(value: seconds, timescale: 1)
removePeriodicTimeObserver()
isTouchingSlider = false
player!.seek(to: targetTime)
addPeriodicTimeObserver()
if player!.rate == 0 {
play()
}
}