axiom-now-playing-musickit

MusicKit 集成（Apple Music）

所需时间：5-10 分钟

关键要点

MusicKit 的 ApplicationMusicPlayer 会自动发布信息到 MPNowPlayingInfoCenter。 播放 Apple Music 内容时，无需手动更新“正在播放”信息。

自动处理的内容

使用 ApplicationMusicPlayer 时：

• 曲目标题、艺人、专辑
• 封面（Apple 的专辑封面）
• 时长和已播放时间
• 播放速率（播放／暂停状态）

系统会为你处理所有 MPNowPlayingInfoCenter 更新。

不会自动处理的内容

• 自定义元数据（章节标记、自定义艺人备注）
• 对标准控制项之外的远程命令进行自定义
• 将 MusicKit 内容与自有内容混合

---

订阅与授权

检查 Music 授权

import MusicKit

func requestMusicAccess() async -> Bool {
    let status = await MusicAuthorization.request()
    return status == .authorized
}

// Check current status without prompting
let currentStatus = MusicAuthorization.currentStatus
// .authorized, .denied, .notDetermined, .restricted

检查 Apple Music 订阅

func checkSubscription() async -> Bool {
    do {
        let subscription = try await MusicSubscription.current
        return subscription.canPlayCatalogContent
    } catch {
        return false
    }
}

// Observe subscription changes
func observeSubscription() {
    Task {
        for await subscription in MusicSubscription.subscriptionUpdates {
            if subscription.canPlayCatalogContent {
                // Full Apple Music access
            } else if subscription.canBecomeSubscriber {
                // Show subscription offer
                showSubscriptionOffer()
            }
        }
    }
}

订阅优惠页

import MusicKit
import StoreKit

// Present Apple Music subscription offer
MusicSubscriptionOffer.Options(
    messageIdentifier: .playMusic,
    itemID: song.id
)

// In SwiftUI
.musicSubscriptionOffer(isPresented: $showOffer, options: offerOptions)

无订阅时的平稳回退

@MainActor
class MusicPlayer: ObservableObject {
    @Published var canPlay = false

    func handlePlayRequest(song: Song) async {
        let authorized = await requestMusicAccess()
        guard authorized else {
            showAuthorizationDeniedAlert()
            return
        }

        do {
            let subscription = try await MusicSubscription.current
            if subscription.canPlayCatalogContent {
                // Full playback
                try await play(song: song)
            } else {
                // Preview only (30-second clips)
                if let previewURL = song.previewAssets?.first?.url {
                    playPreview(url: previewURL)
                }
            }
        } catch {
            handleError(error)
        }
    }
}

---

播放

基本播放

import MusicKit

@MainActor
class MusicKitPlayer {
    private let player = ApplicationMusicPlayer.shared

    func play(song: Song) async throws {
        // ✅ Just play - MPNowPlayingInfoCenter updates automatically
        player.queue = [song]
        try await player.play()

        // ❌ DO NOT manually set nowPlayingInfo here
        // MPNowPlayingInfoCenter.default().nowPlayingInfo = [...] // WRONG!
    }

    func pause() {
        player.pause()
    }

    func stop() {
        player.stop()
    }
}

观察播放状态

@MainActor
class PlayerViewModel: ObservableObject {
    private let player = ApplicationMusicPlayer.shared
    @Published var isPlaying = false
    @Published var currentEntry: ApplicationMusicPlayer.Queue.Entry?
    @Published var playbackTime: TimeInterval = 0

    func observeState() {
        // Observe playback status
        Task {
            for await state in player.state.objectWillChange.values {
                isPlaying = player.state.playbackStatus == .playing
            }
        }

        // Observe current entry (track changes)
        Task {
            for await queue in player.queue.objectWillChange.values {
                currentEntry = player.queue.currentEntry
            }
        }
    }
}

---

队列管理

设置队列

let player = ApplicationMusicPlayer.shared

// Single song
player.queue = [song]

// Album
player.queue = ApplicationMusicPlayer.Queue(album: album)

// Playlist
player.queue = ApplicationMusicPlayer.Queue(playlist: playlist)

// Multiple items
player.queue = ApplicationMusicPlayer.Queue(for: [song1, song2, song3])

// Start at specific item
player.queue = ApplicationMusicPlayer.Queue(for: songs, startingAt: songs[2])

队列操作

// Skip to next
try await player.skipToNextEntry()

// Skip to previous
try await player.skipToPreviousEntry()

// Restart current track
player.restartCurrentEntry()

// Append to queue
try await player.queue.insert(song, position: .afterCurrentEntry)
try await player.queue.insert(song, position: .tail)  // End of queue

// Shuffle and repeat
player.state.shuffleMode = .songs    // .off, .songs
player.state.repeatMode = .all       // .none, .one, .all

观察队列变化

// Current track info
if let entry = player.queue.currentEntry {
    let title = entry.title
    let subtitle = entry.subtitle      // Artist name
    let artwork = entry.artwork         // Artwork for display

    // Get full Song object if needed
    if case .song(let song) = entry.item {
        let albumTitle = song.albumTitle
    }
}

---

混合应用（自有内容 + Apple Music）

如果你的应用同时播放 Apple Music 和自有内容：

import MusicKit

@MainActor
class HybridPlayer {
    private let musicKitPlayer = ApplicationMusicPlayer.shared
    private var avPlayer: AVPlayer?
    private var currentSource: ContentSource = .none

    enum ContentSource {
        case none
        case appleMusic      // MusicKit handles Now Playing
        case ownContent  // We handle Now Playing
    }

    func playAppleMusicSong(_ song: Song) async throws {
        // Switch to MusicKit
        avPlayer?.pause()
        currentSource = .appleMusic

        musicKitPlayer.queue = [song]
        try await musicKitPlayer.play()
        // ✅ MusicKit handles Now Playing automatically
    }

    func playOwnContent(_ url: URL) {
        // Switch to AVPlayer
        musicKitPlayer.pause()
        currentSource = .ownContent

        avPlayer = AVPlayer(url: url)
        avPlayer?.play()

        // ✅ Manually update Now Playing (see axiom-now-playing)
        updateNowPlayingForOwnContent()
    }

    private func updateNowPlayingForOwnContent() {
        var nowPlayingInfo = [String: Any]()
        nowPlayingInfo[MPMediaItemPropertyTitle] = "My Track"
        // ... rest of manual setup
        MPNowPlayingInfoCenter.default().nowPlayingInfo = nowPlayingInfo
    }
}

---

常见错误

// ❌ WRONG - Overwrites MusicKit's automatic Now Playing data
func playAppleMusicSong(_ song: Song) async throws {
    try await ApplicationMusicPlayer.shared.play()

    // ❌ This clears MusicKit's Now Playing info!
    var nowPlayingInfo = [String: Any]()
    nowPlayingInfo[MPMediaItemPropertyTitle] = song.title
    MPNowPlayingInfoCenter.default().nowPlayingInfo = nowPlayingInfo
}

// ✅ CORRECT - Let MusicKit handle it
func playAppleMusicSong(_ song: Song) async throws {
    try await ApplicationMusicPlayer.shared.play()
    // That's it! MusicKit publishes Now Playing automatically.
}

何时在 MusicKit 中使用手动更新

仅在以下情况下覆盖 MPNowPlayingInfoCenter：

• 混入额外元数据（例如播客章节标记）
• 在 Apple Music 内容旁显示自定义内容
• 有特定理由需要替换 MusicKit 的自动行为

默认做法：让 MusicKit 自动管理“正在播放”信息。

资源

文档：/musickit、/musickit/applicationmusicplayer、/musickit/musicsubscription

技能：axiom-now-playing、axiom-now-playing-carplay