Discovering a third-party media-streaming device

At a glance

Project structure

Source bundle/
└── DeviceDiscoveryExtensionDemo/
    ├── CustomMediaDeviceDemo/
    │   ├── Server/
    │   │   ├── ServerApp.swift
    │   │   └── ServerView.swift
    │   ├── Client/
    │   │   ├── ClientApp.swift
    │   │   ├── ClientView.swift
    │   │   ├── DevicePickerView.swift
    │   │   ├── RemoteControlView.swift
    │   │   └── RouteController.swift
    │   └── Protocol/
    │       ├── DemoSession.swift
    │       └── DemoProtocol.swift
    ├── CustomMediaDeviceMacServer/
    │   ├── DemoMacServerApp.swift
    │   └── ContentView.swift
    └── CustomMediaDeviceExtension/
        └── Appex.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 13 project/configuration file(s) and 49 source declaration(s).

Overall architecture

flowchart LR
    N1["ServerApp"]
    N2["ServerView"]
    N3["VideoViewModel"]
    N4["DemoClientSession"]
    N5["SwiftUI / Network APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4
    N4 --> N5

Reference code

DeviceDiscoveryExtensionDemo/CustomMediaDeviceDemo/Server/ServerApp.swift:23 — architecture anchor

@main
struct DataAccessDemoServerApp: App {
    @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate

    var body: some Scene {
        WindowGroup {
            ServerView()
        }
    }
}

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 DeviceDiscoveryExtension.

Ownership and state

classDiagram
    Volume *-- Float : level
    Volume *-- Volume : volume
    State *-- Float : timeRemaining
    State *-- Int : sessionId

Ownership evidence

DeviceDiscoveryExtensionDemo/CustomMediaDeviceDemo/Protocol/DemoSession.swift:26 — stored dependency or nearest verified ownership anchor

    struct Volume {
        var muted = false
        var level: Float = 1.0
    }

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

DeviceDiscoveryExtensionDemo/CustomMediaDeviceDemo/Client/ClientDiscovery.swift:39 — representative execution boundary

class ClientDiscovery: NSObject, CBCentralManagerDelegate, ObservableObject {
    // ...
    let centralManagerQueue = DispatchQueue(label: "centralManager.concurrent.queue", attributes: .concurrent)
    // ...
}

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

DeviceDiscoveryExtensionDemo/CustomMediaDeviceDemo/Protocol/BonjourConnection.swift:20 — representative type boundary

protocol DemoConnectionDelegate: AnyObject {
    // ...
    func didStart(connection: DemoConnection)
    // ...
}

The source explicitly defines local protocol relationships: DemoUdpConnection → DemoConnection, DemoMessageBase → HasMessageTypeParam, DemoClientMessage → DemoMessageBase, DemoServerMessage → DemoMessageBase.

Access control

Reference code

DeviceDiscoveryExtensionDemo/CustomMediaDeviceDemo/Client/ClientView.swift:140 — representative boundary

    private func activateRouteManager() {
        // ...
            print(customRowTapped)
        // ...
    }

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: DataAccessDemoClientApp, DataAccessDemoServerApp, DemoMacServerApp; Controller: ClientSessionController, RouteController; Coordinator: Coordinator; Delegate: AppDelegate, DemoConnectionDelegate; Manager: BTPeripheralManager, RouteManager; Session: DemoClientSession, DemoServerSession, DemoSession; View: ClientDiscoveryView, ClientView, ContentView, DevicePickerView, RemoteControlView; ViewModel: VideoViewModel.
• Protocols: DemoConnectionDelegate, HasMessageTypeParam, DemoMessageBase, DemoConnection.
• Methods: application, toStr, appendInterpolation, didStart, didStop, didSend, didReceive, post.
• Files: DeviceDiscoveryExtensionDemo/CustomMediaDeviceMacServer/DemoMacServerApp.swift, DeviceDiscoveryExtensionDemo/CustomMediaDeviceDemo/Protocol/DemoSession.swift, DeviceDiscoveryExtensionDemo/CustomMediaDeviceDemo/Server/ServerView.swift, DeviceDiscoveryExtensionDemo/CustomMediaDeviceDemo/Client/ClientView.swift, DeviceDiscoveryExtensionDemo/CustomMediaDeviceDemo/Client/DevicePickerView.swift, DeviceDiscoveryExtensionDemo/CustomMediaDeviceDemo/Client/RemoteControlView.swift.

Architecture takeaways

• ServerApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches SwiftUI, Network, AVRouting, CoreBluetooth 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.
• Local protocol relationships provide an explicit substitution boundary.

Source map

• Official Apple documentation