avkit（avkit 命令行）

AVKit

High-level media playback UI built on AVFoundation. Provides system-standard video players, Picture-in-Picture, AirPlay routing, transport controls, and subtitle/caption display. Targets Swift 6.3 / iOS 26+.

Contents

• Setup
• AVPlayerViewController
• SwiftUI VideoPlayer
• Picture-in-Picture
• AirPlay
• Transport Controls and Playback Speed
• Subtitles and Closed Captions
• Common Mistakes
• Review Checklist
• References

Setup

Audio Session Configuration

Configure the audio session and background modes before any playback. Without this, PiP and background audio fail silently.

1. Add the audio background mode to UIBackgroundModes in Info.plist
2. Set the audio session category to .playback

import AVFoundation

func configureAudioSession() {
    let session = AVAudioSession.sharedInstance()
    do {
        try session.setCategory(.playback, mode: .moviePlayback)
        try session.setActive(true)
    } catch {
        print("Audio session configuration failed: \(error)")
    }
}

Imports

import AVKit          // AVPlayerViewController, VideoPlayer, PiP
import AVFoundation   // AVPlayer, AVPlayerItem, AVAsset

AVPlayerViewController

AVPlayerViewController is the standard UIKit player. It provides system playback controls, PiP, AirPlay, subtitles, and frame analysis out of the box. Do not subclass it.

Basic Presentation (Full Screen)

import AVKit

func presentPlayer(from viewController: UIViewController, url: URL) {
    let player = AVPlayer(url: url)
    let playerVC = AVPlayerViewController()
    playerVC.player = player

    viewController.present(playerVC, animated: true) {
        player.play()
    }
}

Inline (Embedded) Playback

Add AVPlayerViewController as a child view controller for inline playback. Call addChild, add the view with constraints, then call didMove(toParent:).

func embedPlayer(in parent: UIViewController, container: UIView, url: URL) {
    let playerVC = AVPlayerViewController()
    playerVC.player = AVPlayer(url: url)

    parent.addChild(playerVC)
    container.addSubview(playerVC.view)
    playerVC.view.translatesAutoresizingMaskIntoConstraints = false
    NSLayoutConstraint.activate([
        playerVC.view.leadingAnchor.constraint(equalTo: container.leadingAnchor),
        playerVC.view.trailingAnchor.constraint(equalTo: container.trailingAnchor),
        playerVC.view.topAnchor.constraint(equalTo: container.topAnchor),
        playerVC.view.bottomAnchor.constraint(equalTo: container.bottomAnchor)
    ])
    playerVC.didMove(toParent: parent)
}

Key Properties

playerVC.showsPlaybackControls = true                    // Show/hide system controls
playerVC.videoGravity = .resizeAspect                    // .resizeAspectFill to crop
playerVC.entersFullScreenWhenPlaybackBegins = false
playerVC.exitsFullScreenWhenPlaybackEnds = true
playerVC.updatesNowPlayingInfoCenter = true              // Auto-updates MPNowPlayingInfoCenter

Use contentOverlayView to add non-interactive views (watermarks, logos) between the video and transport controls.

Delegate

Adopt AVPlayerViewControllerDelegate to respond to full-screen transitions, PiP lifecycle events, interstitial playback, and media selection changes. Use the transition coordinator's animate(alongsideTransition:completion:) to synchronize your UI with full-screen animations.

Display Readiness

Observe isReadyForDisplay before showing the player to avoid a black flash:

let observation = playerVC.observe(\.isReadyForDisplay) { observed, _ in
    if observed.isReadyForDisplay {
        // Safe to show the player view
    }
}

SwiftUI VideoPlayer

The VideoPlayer SwiftUI view wraps AVKit's playback UI.

Basic Usage

import SwiftUI
import AVKit

struct PlayerView: View {
    @State private var player: AVPlayer?

    var body: some View {
        Group {
            if let player {
                VideoPlayer(player: player)
                    .frame(height: 300)
            } else {
                ProgressView()
            }
        }
        .task {
            let url = URL(string: "https://example.com/video.m3u8")!
            player = AVPlayer(url: url)
        }
    }
}

Video Overlay

Add a non-interactive SwiftUI overlay on top of video content.

VideoPlayer(player: player) {
    VStack {
        Spacer()
        HStack {
            Image("logo")
                .resizable()
                .frame(width: 40, height: 40)
                .padding()
            Spacer()
        }
    }
}

UIKit Hosting for Advanced Control

VideoPlayer does not expose all AVPlayerViewController properties. For PiP configuration, delegate callbacks, or playback speed control, wrap AVPlayerViewController in a UIViewControllerRepresentable. See the full pattern in references/avkit-patterns.md.

Picture-in-Picture

PiP lets users watch video in a floating window while using other apps. AVPlayerViewController supports PiP automatically once the audio session is configured. For custom player UIs, use AVPictureInPictureController directly.

Prerequisites

1. Audio session category set to .playback (see Setup)
2. audio background mode in UIBackgroundModes

Standard Player PiP

PiP is enabled by default on AVPlayerViewController. Control automatic activation and inline-to-PiP transitions:

let playerVC = AVPlayerViewController()
playerVC.player = player

// PiP enabled by default; set false to disable
playerVC.allowsPictureInPicturePlayback = true

// Auto-start PiP when app backgrounds (for inline/non-fullscreen players)
playerVC.canStartPictureInPictureAutomaticallyFromInline = true

Restoring the UI When PiP Stops

When the user taps the restore button in PiP, implement the delegate method to re-present your player. Call the completion handler with true to signal the system to finish the restore animation.

func playerViewController(
    _ playerViewController: AVPlayerViewController,
    restoreUserInterfaceForPictureInPictureStopWithCompletionHandler completionHandler: @escaping (Bool) -> Void
) {
    // Re-present or re-embed the player view controller
    present(playerViewController, animated: false) {
        completionHandler(true)
    }
}

Custom Player PiP

For custom player UIs, use AVPictureInPictureController with an AVPlayerLayer or sample buffer content source. Check isPictureInPictureSupported() first. See references/avkit-patterns.md for full custom player and sample buffer PiP patterns.

guard AVPictureInPictureController.isPictureInPictureSupported() else { return }
let pipController = AVPictureInPictureController(playerLayer: playerLayer)
pipController.delegate = self
pipController.canStartPictureInPictureAutomaticallyFromInline = true

Linear Playback During Ads

Prevent seeking during ads or legal notices by toggling requiresLinearPlayback:

// During an ad
playerVC.requiresLinearPlayback = true

// After the ad completes
playerVC.requiresLinearPlayback = false

AirPlay

AVPlayerViewController supports AirPlay automatically. No additional code is required when using the standard player. The system displays the AirPlay button in the transport controls when AirPlay-capable devices are available.

AVRoutePickerView

Add a standalone AirPlay route picker button outside the player UI:

import AVKit

func addRoutePicker(to containerView: UIView) {
    let routePicker = AVRoutePickerView(frame: CGRect(x: 0, y: 0, width: 44, height: 44))
    routePicker.activeTintColor = .systemBlue
    routePicker.prioritizesVideoDevices = true  // Show video-capable routes first
    containerView.addSubview(routePicker)
}

Enabling External Playback

Ensure AVPlayer allows external playback (enabled by default):

player.allowsExternalPlayback = true
player.usesExternalPlaybackWhileExternalScreenIsActive = true

Transport Controls and Playback Speed

Custom Playback Speeds

Provide user-selectable playback speeds in the player UI:

let playerVC = AVPlayerViewController()
playerVC.speeds = [
    AVPlaybackSpeed(rate: 0.5, localizedName: "Half Speed"),
    AVPlaybackSpeed(rate: 1.0, localizedName: "Normal"),
    AVPlaybackSpeed(rate: 1.5, localizedName: "1.5x"),
    AVPlaybackSpeed(rate: 2.0, localizedName: "Double Speed")
]

Use AVPlaybackSpeed.systemDefaultSpeeds to restore the default speed options.

Skipping Behavior

Configure forward/backward skip controls:

playerVC.isSkipForwardEnabled = true
playerVC.isSkipBackwardEnabled = true

Now Playing Integration

AVPlayerViewController updates MPNowPlayingInfoCenter automatically by default. Disable this if you manage Now Playing info manually:

playerVC.updatesNowPlayingInfoCenter = false

Subtitles and Closed Captions

AVKit handles subtitle and closed caption display automatically when the media contains appropriate text tracks. Users control subtitle preferences in Settings > Accessibility > Subtitles & Captioning.

Restricting Subtitle Languages

// Only show English and Spanish subtitle options
playerVC.allowedSubtitleOptionLanguages = ["en", "es"]

Requiring Subtitles

Force subtitles to always display (the user cannot turn them off):

playerVC.requiresFullSubtitles = true

Media Selection (Delegate)

Respond to the user changing subtitle or audio track selection:

func playerViewController(
    _ playerViewController: AVPlayerViewController,
    didSelect mediaSelectionOption: AVMediaSelectionOption?,
    in mediaSelectionGroup: AVMediaSelectionGroup
) {
    if let option = mediaSelectionOption {
        print("Selected: \(option.displayName)")
    }
}

Providing Subtitle Tracks in HLS

Subtitles and closed captions are embedded in HLS manifests. AVKit reads them from AVMediaSelectionGroup on the AVAsset. For local files, use AVMutableComposition to add AVMediaCharacteristic.legible tracks.

Common Mistakes

DON'T: Subclass AVPlayerViewController

Apple explicitly states this is unsupported. It may cause undefined behavior or crash on future OS versions.

// WRONG
class MyPlayerVC: AVPlayerViewController { } // Unsupported

// CORRECT: Use composition with delegation
let playerVC = AVPlayerViewController()
playerVC.delegate = coordinator

DON'T: Skip audio session configuration for PiP

PiP fails silently if the audio session is not set to .playback. Background audio also stops working.

// WRONG: Default audio session
let playerVC = AVPlayerViewController()
playerVC.player = player // PiP won't work

// CORRECT: Configure audio session first
try AVAudioSession.sharedInstance().setCategory(.playback, mode: .moviePlayback)
try AVAudioSession.sharedInstance().setActive(true)
let playerVC = AVPlayerViewController()
playerVC.player = player

DON'T: Forget the PiP restore delegate or its completion handler

Without restoreUserInterfaceForPictureInPictureStopWithCompletionHandler, the system cannot return the user to your player. Failing to call completionHandler(true) leaves the system in an inconsistent state.

// WRONG: No delegate method or missing completionHandler call
// User taps restore in PiP -> nothing happens or animation hangs

// CORRECT
func playerViewController(
    _ playerViewController: AVPlayerViewController,
    restoreUserInterfaceForPictureInPictureStopWithCompletionHandler completionHandler: @escaping (Bool) -> Void
) {
    present(playerViewController, animated: false) {
        completionHandler(true)
    }
}

DON'T: Create AVPlayer in a SwiftUI view's init

Creating the player eagerly causes performance issues. SwiftUI may recreate the view multiple times.

// WRONG: Created on every view init
struct PlayerView: View {
    let player = AVPlayer(url: videoURL) // Re-created on every view evaluation

    var body: some View { VideoPlayer(player: player) }
}

// CORRECT: Use @State and defer creation
struct PlayerView: View {
    @State private var player: AVPlayer?

    var body: some View {
        VideoPlayer(player: player)
            .task { player = AVPlayer(url: videoURL) }
    }
}

Review Checklist

• Audio session category set to .playback with mode:.moviePlayback
• audio background mode added to UIBackgroundModes in Info.plist
• AVPlayerViewController is not subclassed
• PiP restore delegate method implemented and calls completionHandler(true)
• AVPlayer deferred to .task in SwiftUI (not created eagerly)
• canStartPictureInPictureAutomaticallyFromInline set for inline players
• requiresLinearPlayback toggled only during required ad/legal segments
• allowsExternalPlayback enabled on AVPlayer for AirPlay support
• Subtitle language restrictions tested with actual media tracks
• Video gravity set appropriately (.resizeAspect vs .resizeAspectFill)
• isReadyForDisplay observed before showing the player view
• Error handling for network-streamed content (HLS failures, timeouts)

References

• Advanced patterns (custom player UI, interstitials, background playback, error handling): references/avkit-patterns.md
• AVKit framework
• AVPlayerViewController
• VideoPlayer (SwiftUI)
• AVPictureInPictureController
• AVRoutePickerView
• AVPlaybackSpeed
• Configuring your app for media playback
• Adopting Picture in Picture in a Standard Player
• Playing video content in a standard user interface