#まずはArrayの定義。から、Videosのプレイイベントをボタン5種類で発火
ボタンで、NSIntegerで定義した、整数iiに数値を代入し、playVideo()イヴェントへ橋渡し
Playerのセットと、Videoを再生するViewの作成、とコントローラーの作成。
その後、のEndedイベントの作成、と、ii のcount up　、
バックグラウンドモードの作成。（General パネルの中の、BackgroundModeをCapabilityから追加しておく必要がある）


import UIKit
import AVFoundation
import AVKit

class ViewController: UIViewController(){
   @IBOutlet weak scroll1:UIScrollView! 
   var arr = NSArray()
   var arr2 = NSArray()
   var player = AVPlayer()
   var controller = AVPlayerViewController()
   var ii = NSInteger()
   override viewDidLoad() {
      arr = ["url1.mp4", "url2.mp4", "url3.mp4", "url4.mp4", "url5.mp4"]
      arr2 = ["Video Name1", "Video Name2", "Video Name3", "Video Name4", "Video Name5"]
      scroll1.isScrollEnable = yes
      scroll1.showHorizontalScrollIndicator = false
      scroll1.showVerticalScrollIndicator = false
      scroll1.frame = CGRect(x: 0, y: 20, width: self.view.frame.size.width, height: self.view.frame.size.height-20)
      scroll1.contentSize = CGSize(width: self.view.frame.size, 1640)
      let session = AVSession()
      session.setActive(true, options: [])
      session.setCategory(.playback)
      self.becomeFirstResponder() 
   }
   override func viewWillAppear(_ animate: Bool){
      self.becomeFirstResponder()
   }
   override func viewDidAppear(_ animate: Bool){
      self.becomeFirstResponder()
      let application = UIApplication.shared;
      application.endReceivingRemoteControlEvents()
   }
   override func viewWillDisAppear(_ animate: Bool){
      self.becomeFirstResponder()
   }
   override func viewDidDisAppear(_ animate: Bool){
      self.becomeFirstResponder()
      let application = UIApplication.shared;
      application.beginReceivingRemoteControlEvents()
   } 
   override func remoteControlReceived(with event: UIEvent){
      switch event.subtype {
         case .remoteControlPlay:
            controller.player?.play()  
         case .remoteControlStop:
            ii += 1
            controller.player?.play()
         case .remoteControlPause:
            controller.player?.pause()  
      } 
   }
   @IBAction func button1(_ sender: UIButton){
      ii = 0
      playVideo()
   }
   @IBAction func button2(_ sender: UIButton){
      ii = 1
      playVideo()
   }
   @IBAction func button3(_ sender: UIButton){
      ii = 2
      playVideo()
   }
   @IBAction func button4(_ sender: UIButton){
      ii = 3
      playVideo()
   }
   @IBAction func button5(_ sender: UIButton){
      ii = 4
      playVideo()
   }
   func playVideo(){
      let label1 = UILabel()
      label1.frame = CGRect(x: 0, y: self.view.frame.size.height-44, width: self.view.frame.size.width, height: 44)
      label1.textColor = .gray
      scroll1.backgroundColor = .black
      label1.text = arr2[ii]
      self.view.addSubView(label1) 
      let url = NSURL(string: arr[ii])! as URL
      let playItem = AVPlayerItem(url: url)
      player = AVPlayer(playerItem: playItem)
      controller.player = player
      controller.frame = CGRect(x: 0, y: 20, width: scroll1.frame.size.width, height: scroll1.frame.size.height/2-120)
      controller.view.contentMode = .scaleAspectFit
      self.view.addChild(controller)
      self.view.addSubView(controller.view)
      controller.player?.play()
      NotificationCenter.default.addObserver(self, selector: #selector(playerDidFinishPlaying(ended:)), name: .AVPlayerItemDidPlayToEndTime, object: controller.player.currentItem)  
   }
   @objc func playerDidFinishPlaying(ended: AVPlayer){
      if ii > 5 {
         ii = 0
         controller.player?.pause()
      } else {
         ii += 1
         playVideo()
      } 
   }