Working with content from your Mac app using Spatial Preview

At a glance

Project structure

Source bundle/
├── SpatialPreviewSample/
│   ├── SpatialPreviewSample/
│   │   ├── SpatialPreviewSampleApp.swift
│   │   ├── SceneModel.swift
│   │   ├── USDPreviewView.swift
│   │   ├── AnnotationModel.swift
│   │   ├── AnnotationView.swift
│   │   ├── ContentView.swift
│   │   ├── PlaybackModel.swift
│   │   └── SpatialPhotoGalleryView.swift
│   └── SpatialPreviewSample.xcodeproj/
│       ├── .xcodesamplecode.plist
│       └── project.pbxproj
└── 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 3 project/configuration file(s) and 10 source declaration(s).

Overall architecture

flowchart LR
    N1["SpatialPreviewSampleApp"]
    N2["ContentView"]
    N3["PlaybackModel"]
    N4["SpatialPreview APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4

Reference code

SpatialPreviewSample/SpatialPreviewSample/SpatialPreviewSampleApp.swift:15 — architecture anchor

@main
struct SpatialPreviewSampleApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}

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 Spatial Preview.

Ownership and state

classDiagram
    SpatialPreviewSampleApp *-- Logger : sampleApp
    SceneModel o-- USDStage : stage
    SceneModel *-- Entity : rootEntity
    SceneModel o-- Entity : directionalLightEntity

Ownership evidence

SpatialPreviewSample/SpatialPreviewSample/SpatialPreviewSampleApp.swift:12 — stored dependency or nearest verified ownership anchor

extension Logger {
    static let sampleApp = Logger(subsystem: "com.example.apple-samplecode.SpatialPreviewSample", category: "SampleApp")
}

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

SpatialPreviewSample/SpatialPreviewSample/PlaybackModel.swift:68 — representative execution boundary

            playbackTask = Task {
                let renderRate = 1.0 / 30.0 // 30fps
                // ...
            }

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

SpatialPreviewSample/SpatialPreviewSample/SpatialPreviewSampleApp.swift:16 — representative type boundary

@main
struct SpatialPreviewSampleApp: App {
    // ...
            ContentView()
    // ...
}

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

Access control

Reference code

SpatialPreviewSample/SpatialPreviewSample/AnnotationModel.swift:88 — representative boundary

    private func setAttribute<T: USDPrim.Attribute.Value>(token: USDToken,
                                                          value: T,
                                                          variability: USDPrim.Property.Variability = .uniform) {
        // ...
    }

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: SpatialPreviewSampleApp; Model: PlaybackModel, SceneModel; View: AnnotationsView, ContentView, SpatialPhotoGalleryView, USDModelPreviewView, USDPreviewView.
• Protocols: no local protocol declaration in the scanned source.
• Methods: setupStageComponent, loadStage, reload, addAnnotation, loadAnnotations, applyLayout, receiveActiveLayout, shareStage.
• Files: SpatialPreviewSample/SpatialPreviewSample/SpatialPreviewSampleApp.swift, SpatialPreviewSample/SpatialPreviewSample/SceneModel.swift, SpatialPreviewSample/SpatialPreviewSample/USDPreviewView.swift, SpatialPreviewSample/SpatialPreviewSample/ContentView.swift, SpatialPreviewSample/SpatialPreviewSample/PlaybackModel.swift, SpatialPreviewSample/SpatialPreviewSample/SpatialPhotoGalleryView.swift.

Architecture takeaways

• SpatialPreviewSampleApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches SwiftUI, SpatialPreview, USDKit, RealityKit 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