Playing spatial audio

At a glance

Project structure

Source bundle/
└── SpatialAudio/
    ├── App/
    │   └── EntryPoint.swift  # EntryPoint
    ├── Views/
    │   ├── SpatialAudioView.swift  # SpatialAudioView
    │   └── DecibelSlider.swift  # DecibelSlider
    └── Visualizer/
        └── AxisVisualizer.swift  # AxisVisualizer

Structure observations

• The runtime boundary is WindowGroup; the pruned tree lists only files that explain lifecycle, state, or framework integration.
• App code is compact; any explicit model, provider, or entity owner is still shown below rather than collapsed into view-local state.

Overall architecture

flowchart LR
    EntryPoint_1["EntryPoint"]
    WindowGroup_2["WindowGroup"]
    SpatialAudioView_3["SpatialAudioView"]
    RealityView_entity_graph_4["RealityView entity graph"]
    RealityKit_spatial_audio_resources_5["RealityKit spatial-audio resources"]
    EntryPoint_1 --> WindowGroup_2
    WindowGroup_2 --> SpatialAudioView_3
    SpatialAudioView_3 --> RealityView_entity_graph_4
    RealityView_entity_graph_4 --> RealityKit_spatial_audio_resources_5

Reference code

SpatialAudio/App/EntryPoint.swift:11 — the app or executable entry declares the outer scene lifecycle.

struct EntryPoint: App {
    var body: some Scene {
        WindowGroup {
            SpatialAudioView()
        }
    }
}

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
    SpatialAudioView *-- Entity : entity
    SpatialAudioView *-- Decibel : gain
    SpatialAudioView *-- Decibel : directLevel
    SpatialAudioView *-- Decibel : reverbLevel

Ownership evidence

SpatialAudio/Views/SpatialAudioView.swift:14 — representative stored state or the nearest verified lifecycle anchor.

    let entity = Entity()

    /// The gain value of the audio source.
    @State private var gain: Audio.Decibel = .zero

    /// The direct signal that emits from the audio source.
    @State private var directLevel: Audio.Decibel = .zero

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), public, open; unmodified Swift declarations are internal.

Reference code

SpatialAudio/Views/SpatialAudioView.swift:17 — representative visibility boundary.

struct SpatialAudioView: View {
    // ...
    @State private var gain: Audio.Decibel = .zero
    // ...
}

Logic ownership and placement

Design patterns

Naming conventions

• Role suffixes are evidence, not decoration: View: SpatialAudioView.
• Protocols: no app-defined protocol in the reviewed source.
• Commands use verb-led methods: make.
• Files generally match their primary type; Views, Models, Managers, Providers, Components, Systems, and Packages folders describe architectural roles where present.

Architecture takeaways

• Treat EntryPoint 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.
• The compact source does not justify adding repository, coordinator, or protocol layers beyond the model, provider, or view boundary the sample actually declares.

Source map

• Official Apple documentation