ShazamKit Dance Finder with Managed Session

At a glance

Project structure

Source bundle/
├── Shared Source/
│   ├── App/
│   │   ├── ShazamKitDanceFinderApp.swift
│   │   └── ContentView.swift
│   ├── Data/
│   │   ├── NowPlayingViewModel.swift
│   │   └── ResourcesProvider.swift
│   └── Views/
│       ├── DanceCompletionView.swift
│       ├── NowPlayingView.swift
│       ├── RecentDanceRowView.swift
│       └── VideoPlayerView.swift
├── Part 1 - Matching Audio/
│   └── ShazamKitDanceFinder/
│       ├── RecentDancesView.swift
│       └── Matcher.swift
├── Part 2 - Matching Audio with SHManagedSession/
│   └── ShazamKitDanceFinder/
│       └── RecentDancesView.swift
└── Part 3 - Final/
    └── ShazamKitDanceFinder/
        └── RecentDancesView.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 11 project/configuration file(s) and 31 source declaration(s).

Overall architecture

flowchart LR
    N1["ShazamKitDanceFinderApp"]
    N2["ContentView"]
    N3["NowPlayingViewModel"]
    N4["ResourcesProvider"]
    N5["ShazamKit APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4
    N4 --> N5

Reference code

Shared Source/App/ShazamKitDanceFinderApp.swift:10 — architecture anchor

@main
struct ShazamKitDanceFinderApp: App {

    @StateObject private var matcher = Matcher()
    @StateObject private var sceneHandler = SceneHandler()
    @Environment(\.scenePhase) private var scenePhase

    var body: some Scene {
        WindowGroup {
            ContentView()
                .environmentObject(matcher)
                .environmentObject(sceneHandler)
                .onChange(of: scenePhase) { _, newScenePhase in
                    sceneHandler.sceneChanged(to: newScenePhase)
                }
        }
    }
}

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 ShazamKit.

Ownership and state

classDiagram
    RecentDancesView *-- String : emptyStateImageName
    RecentDancesView *-- String : emptyStateTextTitle
    RecentDancesView *-- String : emptyStateTextSubtitle
    RecentDancesView *-- Double : deleteSwipeViewOpacity

Ownership evidence

Part 1 - Matching Audio/ShazamKitDanceFinder/RecentDancesView.swift:20 — stored dependency or nearest verified ownership anchor

    private enum ViewConstants {
        static let emptyStateImageName: String = "EmptyStateIcon"
        static let emptyStateTextTitle: String = "No Dances Yet?"
        static let emptyStateTextSubtitle: String = "Find some music to start learning"
        static let deleteSwipeViewOpacity: Double = 0.5
        // ...
    }

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

Part 1 - Matching Audio/ShazamKitDanceFinder/Matcher.swift:16 — representative execution boundary

@MainActor final class Matcher: ObservableObject {
    // ...
    @Published var isMatching = false
    // ...
}

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

Shared Source/App/ShazamKitDanceFinderApp.swift:11 — representative type boundary

@main
struct ShazamKitDanceFinderApp: App {
    // ...
    @StateObject private var matcher = Matcher()
    // ...
}

No local protocol conformance is claimed as protocol-oriented design; external framework conformances are listed only as dependencies.

Access control

Reference code

Part 1 - Matching Audio/ShazamKitDanceFinder/Matcher.swift:25 — representative boundary

@MainActor final class Matcher: ObservableObject {
    // ...
    private let session: SHSession
    // ...
}

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: ShazamKitDanceFinderApp; Coordinator: Coordinator; Handler: SceneHandler; Provider: ResourcesProvider; View: ContentView, DanceCompletionView, NowPlayingView, RecentDanceRowView, RecentDancesView; ViewModel: NowPlayingViewModel.
• Protocols: no local protocol declaration in the scanned source.
• Methods: sceneChanged, setupPlayback, stopPlayback, addMediaItem, viewMovedToForeground, viewMovedToBackground, updateNowPlayingViewVisibility, hideNowPlayingView.
• Files: Shared Source/App/ShazamKitDanceFinderApp.swift, Shared Source/Data/NowPlayingViewModel.swift, Part 1 - Matching Audio/ShazamKitDanceFinder/RecentDancesView.swift, Part 2 - Matching Audio with SHManagedSession/ShazamKitDanceFinder/RecentDancesView.swift, Part 3 - Final/ShazamKitDanceFinder/RecentDancesView.swift, Shared Source/Views/DanceCompletionView.swift.

Architecture takeaways

• ShazamKitDanceFinderApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches SwiftUI, ShazamKit, AVKit 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.
• The source does not justify labeling the design protocol-oriented.

Source map

• Official Apple documentation