Object tracking with Reality Composer Pro experiences

At a glance

Project structure

Source bundle/
├── ObjectTrackingExperiencesSample/
│   ├── ObjectTrackingExperiencesSampleApp.swift
│   ├── Game/
│   │   └── KeyboardGame.swift
│   ├── AppModel.swift
│   ├── Utils/
│   │   ├── FadeOutComponent.swift
│   │   ├── AppLogger.swift
│   │   └── ObjectTrackingGuide.swift
│   └── Views/
│       ├── ContentView.swift
│       ├── ImmersiveView.swift
│       └── ToggleImmersiveSpaceButton.swift
├── Packages/
│   └── RealityKitContent/
│       ├── Sources/
│       │   └── RealityKitContent/
│       │       └── RealityKitContent.swift
│       └── Package.swift
└── Configuration/
    └── SampleCode.xcconfig

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 5 project/configuration file(s) and 15 source declaration(s).

Overall architecture

flowchart LR
    N1["ObjectTrackingExperiencesSampleApp"]
    N2["ContentView"]
    N3["AppModel"]
    N4["FadeOutSystem"]
    N5["SwiftUI / RealityKit APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4
    N4 --> N5

Reference code

ObjectTrackingExperiencesSample/ObjectTrackingExperiencesSampleApp.swift:9 — architecture anchor

@main
struct ObjectTrackingExperiencesSampleApp: App {

    @State private var appModel = AppModel()

    var body: some Scene {
        WindowGroup {
            ContentView()
                .environment(appModel)
        }

        ImmersiveSpace(id: appModel.immersiveSpaceID) {
            ImmersiveView()
                .environment(appModel)
                .onAppear {
                    appModel.immersiveSpaceState = .open
                }
                .onDisappear {
                    appModel.immersiveSpaceState = .closed
                }
        }
     }
}

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 visionOS.

Ownership and state

classDiagram
    ObjectTrackingExperiencesSampleApp *-- AppModel : appModel
    KeyboardGame o-- Challenge : currentChallenge
    KeyboardGame o-- Challenge : initialChallenge
    Challenge *-- String : description

Ownership evidence

ObjectTrackingExperiencesSample/ObjectTrackingExperiencesSampleApp.swift:12 — stored dependency or nearest verified ownership anchor

@main
struct ObjectTrackingExperiencesSampleApp: App {
    // ...
    @State private var appModel = AppModel()
    // ...
}

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

ObjectTrackingExperiencesSample/Utils/FadeOutComponent.swift:20 — representative execution boundary

@MainActor
class FadeOutSystem: System {
    private static let query = EntityQuery(where: .has(FadeOutComponent.self))
    // ...
}

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

ObjectTrackingExperiencesSample/ObjectTrackingExperiencesSampleApp.swift:10 — representative type boundary

@main
struct ObjectTrackingExperiencesSampleApp: App {
    // ...
    @State private var appModel = AppModel()
    // ...
}

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

Access control

Reference code

ObjectTrackingExperiencesSample/Game/KeyboardGame.swift:13 — representative boundary

class KeyboardGame {
    // ...
    private var initialChallenge: Challenge!
    // ...
}

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: ObjectTrackingExperiencesSampleApp; Component: FadeOutComponent; Model: AppModel; System: FadeOutSystem; View: ContentView, ImmersiveView.
• Protocols: no local protocol declaration in the scanned source.
• Methods: loadChallenges, startGame, respond, encode, update, updateAnimation, setupEntities, setupAttachments.
• Files: ObjectTrackingExperiencesSample/ObjectTrackingExperiencesSampleApp.swift, ObjectTrackingExperiencesSample/Game/KeyboardGame.swift, ObjectTrackingExperiencesSample/AppModel.swift, ObjectTrackingExperiencesSample/Utils/FadeOutComponent.swift, ObjectTrackingExperiencesSample/Views/ContentView.swift, ObjectTrackingExperiencesSample/Views/ImmersiveView.swift.

Architecture takeaways

• ObjectTrackingExperiencesSampleApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches SwiftUI, RealityKit, ARKit, PackageDescription 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