How can I load videos like instagram stories in swift

Question

I'm trying to clone the instagram stories. The problem occurs while playing a video in the AVPlayer and trying to observe when the video is loaded and is started playing so that I can start and pause the timer accordingly

Here is my in the collection view controller

        let url = URL(string: self.user?.stories![indexPath.row].video ?? "")
        cell.storyImage.isHidden = true
        cell.videURL = url
        cell.playVideo()

Here is the code of the collection view cell

    var player:AVPlayer!

func playVideo(){
    player = AVPlayer(url: videURL!)
    player.addObserver(self, forKeyPath: "rate", options: [.old, .new], context: nil)
    let playerLayer = AVPlayerLayer(player: player)
    playerLayer.frame = self.contentView.bounds
    self.contentView.layer.addSublayer(playerLayer)
    player.play()
}


override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    if keyPath == "rate" {
        if player.rate > 0{
            //Trying to start timer here but it runs as soon as the cell is loaded instead of observing when the video actually starts
            
        }
    }
}