Displaying video from connected devices

At a glance

Project structure

Source bundle/
└── DisplayConnectedVideo/
    ├── CaptureManager.swift  # CaptureManager
    ├── DeviceManager.swift  # DeviceManager
    ├── DevicePreview.swift  # DevicePreview, SampleBufferPreview
    ├── ConnectionManager.swift  # Device, ConnectionManager
    ├── DisplayConnectedVideoApp.swift  # DisplayConnectedVideoApp
    └── ContentView.swift  # ContentView

Structure observations

• The runtime boundary is WindowGroup; 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.

Overall architecture

flowchart LR
    DisplayConnectedVideoApp_1["DisplayConnectedVideoApp"]
    WindowGroup_2["WindowGroup"]
    ContentView_3["ContentView"]
    DeviceManager_4["DeviceManager"]
    AVCaptureSession___connected_device_transport_5["AVCaptureSession + connected-device transport"]
    DisplayConnectedVideoApp_1 --> WindowGroup_2
    WindowGroup_2 --> ContentView_3
    ContentView_3 --> DeviceManager_4
    DeviceManager_4 --> AVCaptureSession___connected_device_transport_5

Reference code

DisplayConnectedVideo/DisplayConnectedVideoApp.swift:11 — the app or executable entry declares the outer scene lifecycle.

struct DisplayConnectedVideoApp: App {
    var body: some Scene {
        
        WindowGroup {
            ContentView()
        }
     }
}

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
    ContentView *-- DeviceManager : deviceManager
    ConnectionManager --> DiscoverySession : discoverySession
    CaptureManager *-- AVCaptureSession : captureSession
    DeviceManager --> CaptureManager : captureManager

Ownership evidence

DisplayConnectedVideo/ContentView.swift:12 — representative stored state or the nearest verified lifecycle anchor.

    @State private var deviceManager = DeviceManager()

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, public, open; unmodified Swift declarations are internal.

Reference code

DisplayConnectedVideo/DeviceManager.swift:23 — representative visibility boundary.

    private(set) var devices: [Device] = []
    
    /// The authorization status for camera access when the app launched.
    /// This is set twice when the app is launched for the first time. Initially to `AVCaptureDevice.notDetermined`
    /// then to a value that reflects the choice a person made when prompted for authorization.
    private(set) var initialAuthorizationStatus: AVAuthorizationStatus

Logic ownership and placement

Design patterns

Naming conventions

• Role suffixes are evidence, not decoration: App: DisplayConnectedVideoApp; Manager: CaptureManager, ConnectionManager, DeviceManager; View: ContentView.
• Protocols: no app-defined protocol in the reviewed source.
• Commands use verb-led methods: setUpSession, select, start, observeFlushToResumeDecoding, captureOutput, makeUIView, updateUIView, layoutSubviews.
• Files generally match their primary type; Views, Models, Managers, Providers, Components, Systems, and Packages folders describe architectural roles where present.

Architecture takeaways

• Treat DisplayConnectedVideoApp 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.

Source map

• Official Apple documentation