Integrating MusicKit into your app

At a glance

Project structure

Source bundle/
└── MusicKit2026WWDCSampleApp/
    ├── WorkoutFeedApp.swift
    ├── Views/
    │   ├── MusicKit Views/
    │   │   ├── ScrollingArtworksView.swift
    │   │   ├── ActiveWorkoutView.swift
    │   │   └── Buttons/
    │   │       └── MusicWorkoutButton.swift
    │   └── Workout Specific Views/
    │       ├── MainWorkoutView.swift
    │       ├── WorkoutFeedView.swift
    │       ├── MainView.swift
    │       └── WorkoutSummaryView.swift
    ├── Models/
    │   └── Workout Specific Models/
    │       ├── WorkoutManager.swift
    │       ├── Workout.swift
    │       └── FitPost.swift
    └── ShareSheetView.swift

Structure observations

• Architecturally prominent files are ranked from entry points and role-named declarations; resource-only paths are omitted.
• Primary languages: Swift.
• The verified tree contains 4 project/configuration file(s) and 19 source declaration(s).

Overall architecture

flowchart LR
    N1["WorkoutFeedApp"]
    N2["MainView"]
    N3["WorkoutManager"]
    N4["MusicKit APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4

Reference code

MusicKit2026WWDCSampleApp/WorkoutFeedApp.swift:12 — architecture anchor

@main
struct WorkoutFeedApp: App {
    @State private var workoutManager = WorkoutManager()

    var body: some Scene {
        WindowGroup {
            MainView()
                .environment(workoutManager)
        }
    }
}

Interpretation

The arrows summarize the source-visible entry, role-named types or folders, and framework direction; when nodes come from structural folders, the sequence is a high-level interpretation rather than proof that every adjacent node calls the next. Ownership is claimed only where the next section cites a stored property or assignment. The diagram is intentionally limited to the dominant path into MusicKit.

Ownership and state

classDiagram
    WorkoutFeedApp *-- WorkoutManager : workoutManager
    ScrollingArtworksView o-- CollectionOfArtworks : artworks
    ScrollingArtworksView o-- Element : selection
    ScrollingArtworksView *-- ScrollPosition : scrollPosition

Ownership evidence

MusicKit2026WWDCSampleApp/WorkoutFeedApp.swift:14 — stored dependency or nearest verified ownership anchor

@main
struct WorkoutFeedApp: App {
    @State private var workoutManager = WorkoutManager()
    // ...
}

Composition arrows indicate a source-visible construction expression or locally owned value state; aggregation means the owner stores or receives a dependency without proving exclusive lifetime ownership.

Concurrency, scheduling, and thread safety

Evidence limit: actor isolation, async/await, or Task creation does not by itself prove background-thread execution; Sendable conformance alone does not prove thread-safe mutation.

@MainActor/MainActor.run, DispatchQueue.main, and RunLoop.main are reported as distinct isolation, queue, and event-loop mechanisms. A plain Task is kept separate from Task.detached; neither is labeled as a background thread.

Reference code

MusicKit2026WWDCSampleApp/Models/Workout Specific Models/Workout.swift:12 — representative execution boundary

struct Workout: Equatable, Hashable, Sendable, Identifiable {
    let id = UUID()
    // ...
}

State propagation, frameworks, and dependencies

Evidence limit: an import proves a source-level compilation dependency at the cited line; it does not prove runtime use, architectural adoption, or whether a Swift package is a direct application dependency.

receive(on:) describes downstream delivery scheduling, while subscribe(on:) describes upstream subscription/request/cancel scheduling. An import Combine alone establishes neither behavior nor a Store, reducer, Redux, or other application architecture.

Class and protocol design

MusicKit2026WWDCSampleApp/Views/MusicKit Views/ScrollingArtworksView.swift:12 — representative type boundary

protocol ArtworkProviding: Identifiable, Equatable, Hashable where ID: Sendable & Equatable {
    var artwork: Artwork? { get }
}

The source explicitly defines local protocol relationships: PreviewItem → ArtworkProviding, ApplicationMusicPlayer.Queue.Entry → ArtworkProviding.

Access control

Reference code

MusicKit2026WWDCSampleApp/ShareSheetView.swift:12 — representative boundary

struct ShareSheetView: View {
    @Environment(\.dismiss) private var dismiss
    // ...
}

Swift declarations without a modifier are internal; explicit private, fileprivate, private(set), public, or open entries above are interpreted by language semantics. Objective-C/C samples instead rely on header and implementation boundaries, which are not equivalent to Swift lexical privacy.

Logic ownership and placement

Design patterns

Naming conventions

• Types: App: WorkoutFeedApp; Manager: WorkoutManager; View: ActiveWorkoutView, MainView, MainWorkoutView, ScrollingArtworksView, ShareSheetView.
• Protocols: ArtworkProviding.
• Methods: artwork, post, formatDuration.
• Files: MusicKit2026WWDCSampleApp/WorkoutFeedApp.swift, MusicKit2026WWDCSampleApp/Views/MusicKit Views/ScrollingArtworksView.swift, MusicKit2026WWDCSampleApp/Models/Workout Specific Models/WorkoutManager.swift, MusicKit2026WWDCSampleApp/Views/Workout Specific Views/MainWorkoutView.swift, MusicKit2026WWDCSampleApp/Views/Workout Specific Views/WorkoutFeedView.swift, MusicKit2026WWDCSampleApp/ShareSheetView.swift.

Architecture takeaways

• WorkoutFeedApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches SwiftUI, MusicKit through a deliberately small high-level chain; the detailed API graph remains inside the cited implementation files.
• Stored-property evidence identifies lifecycle collaboration; it does not by itself prove exclusive object ownership.
• Access-control conclusions separate verified language visibility from the likely design rationale.
• Local protocol relationships provide an explicit substitution boundary.

Source map

• Official Apple documentation