Displaying low-latency connected video

At a glance

Project structure

Source bundle/
└── RealityKit-LowLatencyCameraStreaming/
    ├── LowLatencyCameraStreamingApp.swift
    ├── CameraCapture/
    │   ├── CameraCaptureSession.swift
    │   ├── CameraCoordinator.swift
    │   └── VideoDeviceList.swift
    ├── Model/
    │   └── AppModel.swift
    ├── Rendering/
    │   ├── LowLatencyRenderer.swift
    │   └── CameraFeedSharedTexture.swift
    ├── Views/
    │   ├── CameraControlsView.swift
    │   ├── CameraResolutionView.swift
    │   ├── CameraTextureRealityView.swift
    │   └── CameraView.swift
    └── Extensions/
        └── Entity+CameraFeed.swift

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 4 project/configuration file(s) and 20 source declaration(s).

Overall architecture

flowchart LR
    N1["LowLatencyCameraStreamingApp"]
    N2["CameraView"]
    N3["CameraCoordinator"]
    N4["LowLatencyRenderer"]
    N5["RealityKit APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4
    N4 --> N5

Reference code

RealityKit-LowLatencyCameraStreaming/LowLatencyCameraStreamingApp.swift:10 — architecture anchor

@main
struct LowLatencyCameraStreamingApp: App {

    @State private var appModel = AppModel()

    var body: some Scene {
        WindowGroup {
            CameraView()
                .environment(appModel)
        }
        .windowResizability(.contentSize)
     }
}

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 RealityKit.

Ownership and state

classDiagram
    LowLatencyCameraStreamingApp *-- AppModel : appModel
    CameraConfiguration *-- String : cameraID
    CameraConfiguration *-- Double : targetFPS
    CameraCaptureSession *-- Logger : logger

Ownership evidence

RealityKit-LowLatencyCameraStreaming/LowLatencyCameraStreamingApp.swift:13 — stored dependency or nearest verified ownership anchor

@main
struct LowLatencyCameraStreamingApp: 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

RealityKit-LowLatencyCameraStreaming/CameraCapture/CameraCaptureSession.swift:14 — representative execution boundary

enum CameraCaptureEvent: Sendable {
    case didOutputFrame(CMSampleBuffer)
    // ...
}

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

RealityKit-LowLatencyCameraStreaming/LowLatencyCameraStreamingApp.swift:11 — representative type boundary

@main
struct LowLatencyCameraStreamingApp: 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

RealityKit-LowLatencyCameraStreaming/CameraCapture/CameraCaptureSession.swift:42 — representative boundary

actor CameraCaptureSession: NSObject {
    // ...
    private let logger = Logger(subsystem: "com.example.low-latency-streaming", category: "CameraCaptureSession")
    // ...
}

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: LowLatencyCameraStreamingApp; Coordinator: CameraCoordinator; Model: AppModel; Renderer: LowLatencyRenderer; Session: CameraCaptureSession; View: CameraControlsView, CameraResolutionView, CameraTextureRealityView, CameraView.
• Protocols: no local protocol declaration in the scanned source.
• Methods: setupSession, configureOutput, start, stop, setRunning, configureCamera, configureExternalCamera, removeAllInputs.
• Files: RealityKit-LowLatencyCameraStreaming/LowLatencyCameraStreamingApp.swift, RealityKit-LowLatencyCameraStreaming/CameraCapture/CameraCaptureSession.swift, RealityKit-LowLatencyCameraStreaming/Model/AppModel.swift, RealityKit-LowLatencyCameraStreaming/Rendering/LowLatencyRenderer.swift, RealityKit-LowLatencyCameraStreaming/CameraCapture/CameraCoordinator.swift, RealityKit-LowLatencyCameraStreaming/Rendering/CameraFeedSharedTexture.swift.

Architecture takeaways

• LowLatencyCameraStreamingApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches SwiftUI, AVFoundation, RealityKit, CoreImage 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