Implementing SharePlay for immersive spaces in visionOS

At a glance

Project structure

Source bundle/
├── GroupActivities-SharePlayCube/
│   ├── SharePlayCubeApp.swift
│   ├── Models/
│   │   ├── AppModel.swift
│   │   ├── SessionController.swift
│   │   ├── CubeActivityMessagingTypes.swift
│   │   └── ChangeColorActivity.swift
│   ├── Views/
│   │   ├── CubeImmersiveView.swift
│   │   └── SharePlayAttachmentView.swift
│   ├── Info.plist
│   └── SharePlayCubeApp.entitlements
├── Configuration/
│   └── SampleCode.xcconfig
└── GroupActivities-SharePlayCube.xcodeproj/
    ├── .xcodesamplecode.plist
    └── project.pbxproj

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 9 source declaration(s).

Overall architecture

flowchart LR
    N1["SharePlayCubeApp"]
    N2["CubeImmersiveView"]
    N3["AppModel"]
    N4["GroupActivities / SwiftUI APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4

Reference code

GroupActivities-SharePlayCube/SharePlayCubeApp.swift:11 — architecture anchor

@main
struct SharePlayCubeApp: App {
    @State private var appModel = AppModel()

    var body: some Scene {
        ImmersiveSpace {
            CubeImmersiveView()
                .environment(appModel)
        }
        .immersionStyle(selection: .constant(.mixed), in: .mixed)
        .immersiveEnvironmentBehavior(.coexist)
    }
}

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
    SharePlayCubeApp *-- AppModel : appModel
    AppModel o-- SessionController : sessionController
    AppModel o-- CubeColor : color
    SessionController o-- GroupSession : session

Ownership evidence

GroupActivities-SharePlayCube/SharePlayCubeApp.swift:13 — stored dependency or nearest verified ownership anchor

@main
struct SharePlayCubeApp: 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

GroupActivities-SharePlayCube/Models/AppModel.swift:15 — representative execution boundary

@MainActor
@Observable
final class AppModel {
    // ...
    private var sessionController: SessionController?
    // ...
}

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

GroupActivities-SharePlayCube/SharePlayCubeApp.swift:12 — representative type boundary

@main
struct SharePlayCubeApp: 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

GroupActivities-SharePlayCube/Models/AppModel.swift:19 — representative boundary

@MainActor
@Observable
final class AppModel {
    // ...
    private var sessionController: SessionController?
    // ...
}

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: SharePlayCubeApp; Controller: SessionController; Model: AppModel; View: CubeImmersiveView, SharePlayAttachmentView.
• Protocols: no local protocol declaration in the scanned source.
• Methods: endSession, setColor, observeGroupSessions, observeUpdateColorMessages, syncColorChange, observeActiveRemoteParticipants, changeColor, setUpRootEntity.
• Files: GroupActivities-SharePlayCube/SharePlayCubeApp.swift, GroupActivities-SharePlayCube/Models/AppModel.swift, GroupActivities-SharePlayCube/Models/SessionController.swift, GroupActivities-SharePlayCube/Views/CubeImmersiveView.swift, GroupActivities-SharePlayCube/Views/SharePlayAttachmentView.swift, GroupActivities-SharePlayCube/Models/ChangeColorActivity.swift.

Architecture takeaways

• SharePlayCubeApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches GroupActivities, SwiftUI, CoreTransferable, 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