DeliveringIntuitiveMediaPlaybackWithAVKit.md

Delivering Intuitive Media Playback with AVKit

@ WWDC 19

AVKit in the Stack

import AVKit

// 실제로는 url 생성 후 넣어줘야 함 구라쟁이 아저씨 흥
// 1) Create an AVPlayer
let player = AVPlayer(url: "https://my.example.video.m3u8") 

// 2) Create an AVPlayerViewController
let playerViewController = AVPlayerViewController()
playerViewController.player = player

// 3) Show it
present(playerViewController, animated: true)

AVPlayerViewController on iOS: What's new for iOS 13

Full screen callbacks (풀스크린 enter, exit 감지)

• Extends AVPlayerViewControllerDelegate
• Notifies delegate when beginning or ending full screen presentation

@available(iOS 12.0, *)

func playerViewController(_ playerViewController: AVPlayerViewController, willBeginFullScreenPresentationWithAnimationCoordinator coordinator: UIViewControllerTransitionCoordinator)

func playerViewController(_ playerViewController: AVPlayerViewController, willEndFullScreenPresentationWithAnimationCoordinator coordinator: UIViewControllerTransitionCoordinator)

// Implementing AVPlayerViewControllerDelegate's full screen callbacks

func playerViewController(_ playerViewController: AVPlayerViewController, willBeginFullScreenPresentationWithAnimationCoordinator coordinator: UIViewControllerTransitionCoordinator) {
  coordinator.animate(alongsideTransition: { (context) in
		// Add coordinated animations
  }) { (context) in
     if context.isCancelled {
       // Still embedded inline
     } else {
       // Presented full screen
       // Take strong reference to playerViewController if needed
     }
	}
}

• Keep embeded player view controller alive when full screen (풀스크린으로 띄웠는데 원래 플레이어가 사라지면 안 되겠지?!)
  • Deallocating will stop full screen playback
  • Okay to be offscreen or removed from superview / parent
• Use delegate to restore playerViewController or retarget animation

func playerViewController(_ playerViewController: AVPlayerViewController, willEndFullScreenPresentationWithAnimationCoordinator coordinator: UIViewControllerTransitionCoordinator) {
  // If scrolled away, update playerViewController's layout here
}

• Track full screen presentation state with AVPlayerViewControllerDelegate
  • Do not rely on viewWillAppear(_:) and friends
• Works for both embedded and full screen presentations
• Keep embedded player view controller alive when full screen
• Can retarget dismissal animation when embedding inline

AVPlayerViewController in iPad Apps on the Mac

• Exact same API as on iOS
• Picture-in-picture support
  • Including AVPictureInPictureController (also for AppKit)
  • And AVPlayerView, for AppKit-based apps
• Touch Bar, keyboard, and Now Playing support
• Audio and Airplay routing
• Available in macOS 10.15

External Metadata

: 잠금 화면에 표시되는 플레이어 알지? 그런 데에 정보를 잘 보여주려면 메타데이터를 추가해야 돼.

• Supplement missing metadata
  • Title, artwork, and more
• Same API as tvOS

@available(iOS 12.0, *)
extension AVPlayerItem {
  open var externalMetadata: [AVMetadataItem]
}

Improved Support for Custom Controls

• Interactive dismissals
• Landscape support for portrait-only apps
• Keyboard and Touch Bar support
• Now playing management
• Automatic video zoom

Custom Playback Controls

• Set showsPlaybackControls to false
• Present modally
• Add controls to contentOverlayView
• For the best user experience, you should:
  • Override UIViewController methods for status bar, home indicator
  • Pass unhandled touches through your view
  • Let AVKit handle double-tap for video zoom

What's New

• Full screen callbacks
• AVPlayerViewController in iPad apps for the Mac
  • Plus picture-in-picture support for AppKit-based apps
• External metadata
• Improved support for custom controls

AVPlayerViewController on iOS: Best practices

Showing Full Screen

• Covers UIWindowScene coordinate

• Use cases:

  • Splash screen
  • Full screen playback

Splash Screen

• Underneath your UI

• No interaction playback controls

• No need to hide status bar or home indicator

• Possibly looping

• Video should always fill screen

• For video with alpha, custom background color

• Audio is secondary

• Add as child:

  parent.addChild(playerViewController)
  parent.view.addSubview(playerViewController.view) // Or other UIView insertion API
  playerViewController.didMove(toParent: parent)

• Remove from parent:

  playerViewController.willMove(toParent: nil)
  playerViewController.view.removeFromSuperview()
  playerViewController.removeFromParent()

• Disable playback controls:

  playerViewController.showsPlaybackControls = false

• Make video fill entire screen:

  playerViewController.videoGravity = .resizeAspectFill

• Set background color (if needed):

  playerViewController.view.backgroundColor = .clear // Or any other UIColor

• Disable AVPlayer.allowsExternalPlayback

• Configure AVAudioSession for secondary media playback

  • Use .ambient category

• Observe AVAudioSession.silenceSecondaryAudioHintNotification

  • Honor AVAudioSession.secondaryAudioShouldBeSilenceHint

Full Screen Playback

• Present modally
• Use the default modalPresentationStyle <- iOS 13에서 default가 automatic이니까 걍 default 쓰래!
• Do not set AVPlayerViewController.videoGravity
• Use AVPlayerViewControllerDelegate to track full screen presentation state
  • Do not rely on viewWillAppear(_:) and friends
• Set up AVPlayerItem before buffering
  • Set AVPlayer.rate for setting item
• Observe AVPlayer.status and AVPlayerItem.status
  • Don't begin playback until status is .readyToPlay
  • Check error property when staus is .failed
    • Rebuild AVFoundation object if .mediaServicesWereReset
• Enable AVPlayer.usesExternalPlaybackWhileExternalScreenIsActive
• Configure AVAudioSession for .playback

Embeding AVPlayerViewController Inline

• Be prepared to begin and end full screen playback

  • Track state using AVPlayerViewControllerDelegate
  • Keep strong reference to embedded AVPlayerViewController when full screen
  • Retarget dismissal animations when ending full screen presentation

• Leave modalPresentationStyle as .fullScreen

• Can style embedded content without impacting full screen:

  • videoGravity
  • view.layer.cornerRadius, cornerCurve, and maskedCorners
  • view.backgroundColor

• For automatically entering and exiting full screen:

  • entersFullScreenWhenPlaybackBegins
  • exitsFullScreenWhenPlaybackEnds

• Adopt UIViewController containment API

• Add as child:

  parent.addChild(playerViewController)
  containerView.addSubview(playerViewController.view) // Don't put views on top
  playerViewController.didMove(toParent: parent)

• Remove from parent:

  playerViewController.willMove(toParent: nil)
  playerViewController.view.removeFromSuperview()
  playerViewController.removeFromParent()

• Use .contentOverlayView <- 약간 내가 찾던 느낌쓰, 좀 더 공부해 보자.

  • Okay to use before setting player or player item

• Observe .isReadyForDisplay

  • Returns true when first frame is ready

  let token = pvc.observe(\.isReadyForDisplay, options: [.initial]) { [weak self] in
    if observed.isReadyForDisplay {
      // Hide any poster frame or placeholder
    }
  }

Picture-in-picture

• Configure AVAudioSession for .playback

• Add background audio mode entitlement in Xcode

• Don't pause playback when entering background

  • Picture-in-picture may be starting!

• If you must pause, wait until in background

  • Only if picture-in-picture hasn't started
  • Pre-iOS 13: UIApplicationStateBackground
  • iOS 13 and later: UISceneActivationStateBackground

• Track state using AVPlayerViewControllerDelegate

• Application can stop picture-in-picture

  • Toggle AVPlayerViewController.allowsPictureInPicturePlayback

• Be prepared for dismissal when starting

  • AVKit prevents deallocation while active

• Always restore user interface when requested by user

  // Restoring from picture-in-picture using AVPlayerViewControllerDelegate
  func playerViewController(_ playerViewController: AVPlayerViewController, restoreUserInterfaceForPictureInPictureStopWithCompletionHandler completionHandler: @escaping (Bool) -> Void) {
    presentingViewController.present(playerViewController, animated: true) {
      // Must invoke completionHandler
      completionHandler(true)
    }
  }

tvOS 내용은 정리는 딱히 정리하지 않겠다!