musickit

---
name: musickit
description: "Integrate Apple Music playback, catalog search, and Now Playing metadata using MusicKit and MediaPlayer. Use when adding music search, Apple Music subscription flows, queue management, playback controls, remote command handling, or Now Playing info to iOS apps."
---

# MusicKit

Search the Apple Music catalog, manage playback with `ApplicationMusicPlayer`,
check subscriptions, and publish Now Playing metadata via `MPNowPlayingInfoCenter`
and `MPRemoteCommandCenter`.

## Contents

- [Setup](#setup)
- [Workflow](#workflow)
- [Authorization](#authorization)
- [Catalog Search](#catalog-search)
- [Subscription Checks](#subscription-checks)
- [Playback with ApplicationMusicPlayer](#playback-with-applicationmusicplayer)
- [Queue Management](#queue-management)
- [Now Playing Info](#now-playing-info)
- [Remote Command Center](#remote-command-center)
- [Common Mistakes](#common-mistakes)
- [Review Checklist](#review-checklist)
- [References](#references)

## Workflow

1. Verify the MusicKit App Service, bundle identifier, purpose string, and background-audio mode before debugging code.
2. Request authorization, then model every non-authorized state explicitly.
3. Search or load catalog content and check `MusicSubscription.current` before queueing playback.
4. Choose `ApplicationMusicPlayer` for app-scoped playback; wire Now Playing and remote commands only when the app owns those surfaces.
5. Test authorized, denied, unsubscribed, offline, queue failure, interruption, and track-change states. Fix the smallest failing layer, restore the fixture, and rerun the same state matrix.

## Setup

### Project Configuration

1. Enable the **MusicKit App Service** for the app's explicit bundle ID in the Apple Developer portal so MusicKit can generate developer tokens automatically.
2. Add `NSAppleMusicUsageDescription` to Info.plist explaining why the app accesses the user's media library.
3. For background playback, add the `audio` background mode to `UIBackgroundModes`.

### Imports

```swift
import MusicKit       // Catalog, auth, playback
import MediaPlayer    // MPRemoteCommandCenter, MPNowPlayingInfoCenter
```

## Authorization

Request permission before accessing the user's music data or playing Apple Music
content. `request()` presents Apple's consent dialog when necessary; use
`currentStatus` to read the current setting without prompting.

```swift
func requestMusicAccess() async -> MusicAuthorization.Status {
    let status = await MusicAuthorization.request()
    switch status {
    case .authorized:
        // Full access to MusicKit APIs
        break
    case .denied, .restricted:
        // Show guidance to enable in Settings
        break
    case .notDetermined:
        break
    @unknown default:
        break
    }
    return status
}

// Check current status without prompting
let current = MusicAuthorization.currentStatus
```

## Catalog Search

Use `MusicCatalogSearchRequest` to search the Apple Music catalog. Catalog lookup
can fetch Apple Music resources, but playback of subscription catalog content
must still be gated on `MusicSubscription.current.canPlayCatalogContent`.

```swift
func searchCatalog(term: String) async throws -> MusicItemCollection<Song> {
    var request = MusicCatalogSearchRequest(term: term, types: [Song.self])
    request.limit = 25

    let response = try await request.response()
    return response.songs
}
```

### Displaying Results

```swift
for song in songs {
    print("\(song.title) by \(song.artistName)")
    if let artwork = song.artwork {
        let url = artwork.url(width: 300, height: 300)
        // Load artwork from url
    }
}
```

## Subscription Checks

Check whether the user has an active Apple Music subscription before offering playback features.

```swift
func checkSubscription() async throws -> Bool {
    let subscription = try await MusicSubscription.current
    return subscription.canPlayCatalogContent
}

// Observe subscription changes
func observeSubscription() async {
    for await subscription in MusicSubscription.subscriptionUpdates {
        if subscription.canPlayCatalogContent {
            // Enable full playback UI
        } else {
            // Show subscription offer
        }
    }
}
```

### Offering Apple Music

Present the Apple Music subscription offer sheet when the user is not subscribed.
Check `canBecomeSubscriber` first, and pass `MusicSubscriptionOffer.Options` or
`onLoadCompletion` when the sheet needs contextual metadata or load-error handling.

```swift
import MusicKit
import SwiftUI

struct MusicOfferView: View {
    @State private var showOffer = false

    var body: some View {
        Button("Subscribe to Apple Music") {
            Task {
                let subscription = try? await MusicSubscription.current
                showOffer = subscription?.canBecomeSubscriber == true
            }
        }
        .musicSubscriptionOffer(
            isPresented: $showOffer,
            options: .default,
            onLoadCompletion: { error in
                if let error {
                    // Surface loading errors in app UI or diagnostics.
                    print(error)
                }
            }
        )
    }
}
```

## Playback with ApplicationMusicPlayer

`ApplicationMusicPlayer` plays Apple Music content independently from the Music app. It does not affect the system player's state.

```swift
let player = ApplicationMusicPlayer.shared

func playSong(_ song: Song) async throws {
    player.queue = [song]
    try await player.play()
}

func pause() {
    player.pause()
}

func skipToNext() async throws {
    try await player.skipToNextEntry()
}
```

### Observing Playback State

```swift
func observePlayback() {
    // player.state is an @Observable property
    let state = player.state
    switch state.playbackStatus {
    case .playing:
        break
    case .paused:
        break
    case .stopped, .interrupted, .seekingForward, .seekingBackward:
        break
    @unknown default:
        break
    }
}
```

## Queue Management

Build and manipulate the playback queue using `ApplicationMusicPlayer.Queue`.

```swift
// Initialize with multiple items
func playAlbum(_ album: Album) async throws {
    player.queue = [album]
    try await player.play()
}

// Append songs to the existing queue
func appendToQueue(_ songs: [Song]) async throws {
    try await player.queue.insert(songs, position: .tail)
}

// Insert song to play next
func playNext(_ song: Song) async throws {
    try await player.queue.insert(song, position: .afterCurrentEntry)
}
```

## Now Playing Info

Update `MPNowPlayingInfoCenter` so the Lock Screen, Control Center, and CarPlay
display current track metadata. This is essential when playing custom audio
(non-MusicKit sources). `ApplicationMusicPlayer` handles this automatically for
Apple Music content.

```swift
import MediaPlayer

func updateNowPlaying(title: String, artist: String, duration: TimeInterval, elapsed: TimeInterval) {
    var info = [String: Any]()
    info[MPMediaItemPropertyTitle] = title
    info[MPMediaItemPropertyArtist] = artist
    info[MPMediaItemPropertyPlaybackDuration] = duration
    info[MPNowPlayingInfoPropertyElapsedPlaybackTime] = elapsed
    info[MPNowPlayingInfoPropertyPlaybackRate] = 1.0
    info[MPNowPlayingInfoPropertyMediaType] = MPNowPlayingInfoMediaType.audio.rawValue

    MPNowPlayingInfoCenter.default().nowPlayingInfo = info
}

func clearNowPlaying() {
    MPNowPlayingInfoCenter.default().nowPlayingInfo = nil
}
```

### Adding Artwork

```swift
func setArtwork(_ image: UIImage) {
    let artwork = MPMediaItemArtwork(boundsSize: image.size) { _ in image }
    var info = MPNowPlayingInfoCenter.default().nowPlayingInfo ?? [:]
    info[MPMediaItemPropertyArtwork] = artwork
    MPNowPlayingInfoCenter.default().nowPlayingInfo = info
}
```

## Remote Command Center

Register handlers for `MPRemoteCommandCenter` to respond to Lock Screen controls,
AirPods tap gestures, and CarPlay buttons.

```swift
func setupRemoteCommands() {
    let center = MPRemoteCommandCenter.shared()

    center.playCommand.addTarget { _ in
        resumePlayback()
        return .success
    }

    center.pauseCommand.addTarget { _ in
        pausePlayback()
        return .success
    }

    center.nextTrackCommand.addTarget { _ in
        skipToNext()
        return .success
    }

    center.previousTrackCommand.addTarget { _ in
        skipToPrevious()
        return .success
    }

    // Disable commands you do not support
    center.seekForwardCommand.isEnabled = false
    center.seekBackwardCommand.isEnabled = false
}
```

### Scrubbing Support

```swift
func enableScrubbing() {
    let center = MPRemoteCommandCenter.shared()
    center.changePlaybackPositionCommand.addTarget { event in
        guard let positionEvent = event as? MPChangePlaybackPositionCommandEvent else {
            return .commandFailed
        }
        seek(to: positionEvent.positionTime)
        return .success
    }
}
```

## Common Mistakes

| Mistake | Fix |
|---|---|
| Debugging authorization before configuring the App Service and purpose string | Verify service, bundle ID, and `NSAppleMusicUsageDescription` first. |
| Queueing catalog content without a subscription gate | Check `canPlayCatalogContent`; offer subscription only when `canBecomeSubscriber`. |
| Using `SystemMusicPlayer` for app-owned playback | Use `ApplicationMusicPlayer`; the system player changes the Music app's global queue. |
| Publishing Now Playing metadata once | Refresh it on track, duration, rate, and elapsed-time changes. |
| Registering unsupported remote commands | Disable them; supported handlers must perform the action and return `.success`. |

## Review Checklist

- [ ] MusicKit App Service enabled for the app's explicit bundle ID
- [ ] `NSAppleMusicUsageDescription` added to Info.plist
- [ ] `MusicAuthorization.request()` called before any MusicKit access
- [ ] Subscription checked before attempting catalog playback
- [ ] `canBecomeSubscriber` checked before presenting a subscription offer
- [ ] `hasCloudLibraryEnabled` checked before library writes
- [ ] `ApplicationMusicPlayer` used (not `SystemMusicPlayer`) for app-scoped playback
- [ ] Background audio mode enabled if music plays in background
- [ ] Now Playing info updated on every track change (for custom audio)
- [ ] Remote command handlers return `.success` for supported commands
- [ ] Unsupported remote commands disabled with `isEnabled = false`
- [ ] Artwork provided in Now Playing info for Lock Screen display
- [ ] Elapsed playback time updated periodically for scrubber accuracy
- [ ] Subscription offer presented when user lacks Apple Music subscription

## References

- Extended patterns (SwiftUI integration, genre browsing, playlist management): [references/musickit-patterns.md](references/musickit-patterns.md)
- [MusicKit framework](https://sosumi.ai/documentation/musickit)
- [Using automatic developer token generation for Apple Music API](https://sosumi.ai/documentation/musickit/using-automatic-token-generation-for-apple-music-api)
- [MusicAuthorization](https://sosumi.ai/documentation/musickit/musicauthorization)
- [ApplicationMusicPlayer](https://sosumi.ai/documentation/musickit/applicationmusicplayer)
- [MusicCatalogSearchRequest](https://sosumi.ai/documentation/musickit/musiccatalogsearchrequest)
- [MusicSubscription](https://sosumi.ai/documentation/musickit/musicsubscription)
- [canPlayCatalogContent](https://sosumi.ai/documentation/musickit/musicsubscription/canplaycatalogcontent)
- [canBecomeSubscriber](https://sosumi.ai/documentation/musickit/musicsubscription/canbecomesubscriber)
- [hasCloudLibraryEnabled](https://sosumi.ai/documentation/musickit/musicsubscription/hascloudlibraryenabled)
- [MusicCatalogChartsRequest initializer](https://sosumi.ai/documentation/musickit/musiccatalogchartsrequest/init(genre:kinds:types:))
- [musicSubscriptionOffer(isPresented:options:onLoadCompletion:)](https://sosumi.ai/documentation/swiftui/view/musicsubscriptionoffer(ispresented:options:onloadcompletion:))
- [MPRemoteCommandCenter](https://sosumi.ai/documentation/mediaplayer/mpremotecommandcenter)
- [MPNowPlayingInfoCenter](https://sosumi.ai/documentation/mediaplayer/mpnowplayinginfocenter)
- [NSAppleMusicUsageDescription](https://sosumi.ai/documentation/bundleresources/information-property-list/nsapplemusicusagedescription)