Swift Splash

At a glance

Project structure

Source bundle/
├── SwiftSplash/SwiftSplashApp.swift  # SwiftSplash
├── Packages/SwiftSplashTrackPieces/Sources/SwiftSplashTrackPieces/Components/MarkerComponents.swift  # PlaceStartPieceUIMarkerComponent, EditUILocationMarkerComponent, RideAnimationComponent
├── Packages/SwiftSplashTrackPieces/Sources/SwiftSplashTrackPieces/Components/ConnectableStateComponent.swift  # ConnectableStateComponent
├── Packages/SwiftSplashTrackPieces/Sources/SwiftSplashTrackPieces/Components/CustomBillboardComponent.swift  # CustomBillboardComponent
├── SwiftSplash/Views/ContentView.swift  # ContentView
├── SwiftSplash/Data & State/AppState.swift  # TilePieceKey, ConnectionPointType, AppState
├── Packages/SwiftSplashTrackPieces/Sources/SwiftSplashTrackPieces/Components/Connectable.swift  # ConnectableComponent
├── SwiftSplash/Views/TrackBuildingView.swift  # TrackBuildingView, AttachmentIDs
└── Packages/SwiftSplashTrackPieces/Package.realitycomposerpro/ProjectData/main.json  # authored RealityKit content

Structure observations

• The runtime boundary is WindowGroup + ImmersiveSpace; the pruned tree lists only files that explain lifecycle, state, or framework integration.
• App code is split into role-named views, models, managers, providers, components, or systems.
• Authored .reality or Reality Composer Pro content is a real implementation boundary; Swift loads or drives it rather than reproducing its entity graph.

Overall architecture

flowchart LR
    SwiftSplash_1["SwiftSplash"]
    WindowGroup___ImmersiveSpace_2["WindowGroup + ImmersiveSpace"]
    ContentView_3["ContentView"]
    AppState_4["AppState"]
    RealityView_entity_graph_5["RealityView entity graph"]
    RealityKit_components_and_systems_6["RealityKit components and systems"]
    SwiftSplash_1 --> WindowGroup___ImmersiveSpace_2
    WindowGroup___ImmersiveSpace_2 --> ContentView_3
    ContentView_3 --> AppState_4
    AppState_4 --> RealityView_entity_graph_5
    RealityView_entity_graph_5 --> RealityKit_components_and_systems_6

Reference code

SwiftSplash/SwiftSplashApp.swift:14 — the app or executable entry declares the outer scene lifecycle.

struct SwiftSplash: App {
    // ...
}

The diagram is a responsibility flow, not a claim that every adjacent node directly calls the next. It keeps scene ownership, shared state, RealityKit content, and framework-provider work at separate levels.

Ownership and state

classDiagram
    SwiftSplash *-- AppState : appState
    ContentView o-- AppState : appState
    AppState *-- ARKitSession : session
    SwiftSplash *-- ImmersionStyle : immersionStyle

Ownership evidence

SwiftSplash/SwiftSplashApp.swift:19 — representative stored state or the nearest verified lifecycle anchor.

@main
@MainActor
struct SwiftSplash: App {
    // ...
    @State private var appState = AppState()
    // ...
}

Ownership here is deliberately narrow: @Environment and weak references are shared links, initialized @State or stored services are lifecycle ownership, and a RealityView content closure owns additions to its entity graph without making the SwiftUI view a reference-type owner.

Class and protocol design

The source defines no local substitution protocol in the reviewed boundary. Its protocol use is framework-facing (App, View, RealityKit/ARKit protocols, or platform adapters), so this document does not label the whole app protocol-oriented.

Access control

No reviewed declaration uses fileprivate, private(set), open; unmodified Swift declarations are internal.

Reference code

Packages/SwiftSplashTrackPieces/Sources/SwiftSplashTrackPieces/Systems/CustomBillboardSystem.swift:21 — representative visibility boundary.

    private let arkitSession = ARKitSession()
    private let worldTrackingProvider = WorldTrackingProvider()
    
    public init(scene: RealityKit.Scene) {
        setUpSession()
    }

Logic ownership and placement

Design patterns

Naming conventions

• Role suffixes are evidence, not decoration: View: ContentView, EditTrackPieceView, PieceShelfTrackButtonsView, PieceShelfView, PlaceStartPieceView.
• ECS names pair data and behavior: components ConnectableComponent, ConnectableStateComponent, CustomBillboardComponent, PlaceStartPieceUIMarkerComponent; systems CustomBillboardSystem.
• Protocols: no app-defined protocol in the reviewed source.
• Commands use verb-led methods: the code-light sample has no separate command layer.
• Files generally match their primary type; Views, Models, Managers, Providers, Components, Systems, and Packages folders describe architectural roles where present.

Architecture takeaways

• Treat SwiftSplash as the owner of scene declarations, not as the owner of every RealityKit entity created later.
• Keep view-local interaction in SwiftUI, but move provider sessions, playback resources, shared game state, or transport state into a stable owner when their lifetime exceeds one render pass.
• Run ARKit providers for the scene lifetime and consume their asynchronous updates in cancellable tasks; map anchors to entities at the boundary.
• Use RealityKit components for per-entity data and systems for repeated simulation instead of a monolithic view model.
• Model immersive-space open, transition, and close states explicitly so windows and immersive content cannot drift apart.

Source map

• Official Apple documentation