Swift observevalueforkeypath + loadedTimeRanges only called limited times - swift

Question

I am trying to create a video player with AVPlayer.Videos load from youtube. I want when video current time changes, my uiSlider and my time label can update. I am using "observeValueForKeyPath" method to catch "loadedTimeRanges" status from player item. Here is my code:
override func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutablePointer<Void>) {
print("keyPath: \(keyPath)")
let playerItem:AVPlayerItem = object as! AVPlayerItem
if keyPath == "status" {
if playerItem.status == AVPlayerItemStatus.ReadyToPlay{
print("AVPlayerItemStatusReadyToPlay")
} else if playerItem.status == AVPlayerItemStatus.Failed {
print("AVPlayerItemStatusFailed")
}
} else if keyPath == "loadedTimeRanges" {
let currentTime = playerItem.currentTime().seconds
let totalDuration = playerItem.duration.seconds
print("value: \(Float(currentTime/totalDuration))")
self.monitoringPlayback(player.currentItem!)
self.slider.setValue(Float(currentTime/totalDuration), animated: false)
}
}
func monitoringPlayback(playerItem:AVPlayerItem) {
let currentSecond:Double = playerItem.currentTime().seconds
self.updateVideoSlider(currentSecond)
let timeString = self.updateTime(playerItem.duration.seconds - currentSecond)
print("time string: \(timeString)")
self.lblTime.text = timeString
}
However, the "observeValueForKeyPath" method is only called 20-22 times everytime. Please, check the log screenshot: https://gyazo.com/5ca57ba532689d83aea855ae41387f53
It's the first time I use this method, so maybe I didn't understand how it work. If anyone who know it, please tell me why. Thanks for reading my question.

Answer 1

it, easy
var rightCurrentTimer: UILabel = {
let lbl = UILabel()
lbl.text = "00:00"
lbl.textColor = .white
lbl.translatesAutoresizingMaskIntoConstraints = false
lbl.font = UIFont.systemFont(ofSize: 11)
return lbl
}()
let leftWhatTimePlayed:UILabel = {
let lbl = UILabel()
lbl.translatesAutoresizingMaskIntoConstraints = false
lbl.textColor = .white
lbl.text = "00:00"
lbl.font = UIFont.systemFont(ofSize: 11)
return lbl
}()
let interval = CMTime(value: 1, timescale: 1)
player?.addPeriodicTimeObserver(forInterval: interval, queue: DispatchQueue.main, using: { (timeProgress) in
let secondsPlay = CMTimeGetSeconds(timeProgress)
let secondString = String(format:"%02d" , Int(secondsPlay) % 60 )
let minutesString = String(format:"%02d", Int(secondsPlay) / 60)
self.leftWhatTimePlayed.text = "\(minutesString):\(secondString)"
if let duration = self.player?.currentItem?.duration {
let totalSecond = CMTimeGetSeconds(duration)
let whatSecondIsPlay = totalSecond - secondsPlay
let secondsIsPlay = String(format:"%02d" , Int(whatSecondIsPlay) % 60)
let minutesIsPlay = String(format: "%02d", Int(whatSecondIsPlay) / 60)
self.rightCurrentTimer.text = "\(minutesIsPlay):\(secondsIsPlay)"
self.videoLengthTimeSlider.value = Float(secondsPlay/totalSecond)
}
})