Swift conversion of code for article on multiple video playback in iOS (original article/source: http://iosguy.com/2012/01/11/multiple-video-playback-on-ios/)

MNGVideoPlayerView.swift

//
//  Created by Tommie N. Carter, Jr., MBA on 2/12/16.
//  Copyright © 2016 MING Technology. All rights reserved.
//

import UIKit
import AVFoundation

class MNGVideoPlayerView: UIView {

    /*
    // Only override drawRect: if you perform custom drawing.
    // An empty implementation adversely affects performance during animation.
    override func drawRect(rect: CGRect) {
        // Drawing code
    }
    */
    override class func layerClass () -> AnyClass {
        return AVPlayerLayer.self
    }
    func player () -> AVPlayer {
        return (self.layer as! AVPlayerLayer).player!
    }
    
    func setPlayer(player:AVPlayer) {
        (self.layer as! AVPlayerLayer).player = player
    }
    func setVideoFillMode(fillMode:String) {
        let playerLayer = (self.layer as! AVPlayerLayer)
        playerLayer.videoGravity = fillMode
    }

}

MNGVideoPlayerViewController.swift

//
//  Created by Tommie N. Carter, Jr., MBA on 2/12/16.
//  Copyright © 2016 MING Technology. All rights reserved.
//

import UIKit
import AVFoundation

class MNGVideoPlayerViewController: UIViewController {

    
    
    let kTracksKey        = "tracks";
    let kStatusKey        = "status";
    let kRateKey          = "rate";
    let kPlayableKey      = "playable";
    let kCurrentItemKey   = "currentItem";
    let kTimedMetadataKey = "currentItem.timedMetadata";
    
    var _URL:NSURL? = nil
    var player:AVPlayer? = nil
    var playerItem:AVPlayerItem? = nil
    var playerView:MNGVideoPlayerView? = nil
    var AVPlayerDemoPlaybackViewControllerStatusObservationContext = UnsafeMutablePointer<Void>()
    var AVPlayerDemoPlaybackViewControllerCurrentItemObservationContext = UnsafeMutablePointer<Void>()
    var AVPlayerDemoPlaybackViewControllerStatusObservation = UnsafeMutablePointer<Void>()
    
    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    

    // MARK: - Public methods
    func setURL(url:NSURL) {
        self._URL = url
        let asset = AVURLAsset(URL: self._URL!)
        let requestedKeys = [kTracksKey,kPlayableKey]
        asset.loadValuesAsynchronouslyForKeys(requestedKeys) { () -> Void in
            self.prepareToPlayAsset(asset, withKeys: requestedKeys)
        }
    }
    func prepareToPlayAsset(asset:AVURLAsset, withKeys requestedKeys:NSArray) {
        var error:NSErrorPointer = nil
        
        for thisKey in requestedKeys {
            let keyStatus = asset.statusOfValueForKey(thisKey as! String, error: error)
            if keyStatus == .Failed {
                return
            }
        }
        
        if !asset.playable {
            return
        }
        if (self.playerItem != nil) {
            self.playerItem?.removeObserver(self, forKeyPath: kStatusKey)
            NSNotificationCenter.defaultCenter().removeObserver(self, name: AVPlayerItemDidPlayToEndTimeNotification, object: self.playerItem)
        }
        self.playerItem = AVPlayerItem(asset: asset)
        self.playerItem?.addObserver(self, forKeyPath: kStatusKey, options: [.Initial,.New], context: AVPlayerDemoPlaybackViewControllerStatusObservationContext)
        
        if (self.player == nil) {
            self.player = AVPlayer(playerItem: self.playerItem!)
            self.player?.addObserver(self, forKeyPath: kCurrentItemKey, options: [.Initial,.New], context: AVPlayerDemoPlaybackViewControllerCurrentItemObservationContext)
        }
        
        if self.player?.currentItem! != self.playerItem! {
            self.player?.replaceCurrentItemWithPlayerItem(self.playerItem!)
        }
    }
    
    // MARK: - Key Value Observing
    override func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutablePointer<Void>) {
        
        if context == AVPlayerDemoPlaybackViewControllerStatusObservation {
            
            let status:Int = (change![NSKeyValueChangeNewKey]?.integerValue)!
            if status == AVPlayerStatus.ReadyToPlay.rawValue  {
                self.player?.play()
            }
        } else if context == AVPlayerDemoPlaybackViewControllerCurrentItemObservationContext {
            
            let newPlayerItem = change![NSKeyValueChangeNewKey] as? AVPlayerItem
            
            if newPlayerItem != nil {
                self.playerView?.setPlayer(self.player!)
                self.playerView?.setVideoFillMode(AVLayerVideoGravityResizeAspect)
            }
            
        } else {
            
            super.observeValueForKeyPath(keyPath, ofObject: object, change: change, context: context)
            
        }
    }
    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        // Get the new view controller using segue.destinationViewController.
        // Pass the selected object to the new view controller.
    }
    */

}