Receiving Voice and Text Communications on a Local Network

At a glance

Project structure

Source bundle/
├── SimplePush/
│   └── SimplePush/
│       ├── SimplePushApp.swift
│       ├── UI/
│       │   ├── DirectoryViewModel.swift
│       │   ├── SettingsViewModel.swift
│       │   ├── UserViewModel.swift
│       │   ├── MessagingViewModel.swift
│       │   └── AppManager.swift
│       ├── Managers/
│       │   └── CallManager.swift
│       └── AppDelegate.swift
├── SimplePushKit/
│   └── SimplePushKit/
│       └── Networking/
│           ├── RequestResponseSession.swift
│           └── ConnectionOptions.swift
└── SimplePushServer/
    └── SimplePushServer/
        ├── Client.swift
        └── main.swift

Structure observations

• Architecturally prominent files are ranked from entry points and role-named declarations; resource-only paths are omitted.
• Primary languages: C/Objective-C header, Swift.
• The verified tree contains 15 project/configuration file(s) and 83 source declaration(s).

Overall architecture

flowchart LR
    N1["SimplePushApp"]
    N2["DirectoryView"]
    N3["DirectoryViewModel"]
    N4["SimplePushProvider"]
    N5["Network APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4
    N4 --> N5

Reference code

SimplePush/SimplePush/SimplePushApp.swift:11 — architecture anchor

@main
struct SimplePushApp: App {
    @UIApplicationDelegateAdaptor private var appDelegate: AppDelegate
    // ...
}

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 Network Extension.

Ownership and state

classDiagram
    SimplePushApp o-- AppDelegate : appDelegate
    SimplePushApp *-- RootViewCoordinator : rootViewCoordinator
    DirectoryViewModel o-- State : state
    DirectoryViewModel o-- User : connectedUser

Ownership evidence

SimplePush/SimplePush/SimplePushApp.swift:13 — stored dependency or nearest verified ownership anchor

@main
struct SimplePushApp: App {
    @UIApplicationDelegateAdaptor private var appDelegate: AppDelegate
    // ...
}

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

SimplePush/SimplePush/AppDelegate.swift:14 — representative execution boundary

class AppDelegate: NSObject, UIApplicationDelegate {
    private let dispatchQueue = DispatchQueue(label: "AppDelegate.dispatchQueue")
    // ...
}

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

SimplePushKit/SimplePushKit/Coding/KeyCodable.swift:21 — representative type boundary

protocol KeyCodable {
    associatedtype Key: Hashable
    var keymap: [Key: Codable.Type] { get }
}

The source explicitly defines local protocol relationships: Invite → Routable, KeyCoder → KeyCodable, TextMessage → Routable, RootViewCoordinator → Presenter, UserViewModel → Presenter.

Access control

Reference code

SimplePush/Common/Networking/BaseChannel.swift:23 — representative boundary

class BaseChannel {
    // ...
    private(set) lazy var messagePublisher: AnyPublisher<Codable, Never> = internalMessageSubject.dropNil()
    // ...
}

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: SimplePushApp; Client: Client; Command: Command; Coordinator: HeartbeatCoordinator, RootViewCoordinator; Delegate: AppDelegate; Manager: CallManager, MessagingManager, PushConfigurationManager, SettingsManager, UserManager; Monitor: HeartbeatMonitor; Provider: SimplePushProvider.
• Protocols: KeyCodable, Routable, Presenter.
• Methods: view, userView, sendCall, receiveCall, endCall, cleanUpActiveCall, requestCallKitTransaction, updateCallHandle.
• Files: SimplePush/SimplePush/SimplePushApp.swift, SimplePush/SimplePush/UI/DirectoryViewModel.swift, SimplePush/SimplePush/Managers/CallManager.swift, SimplePush/SimplePush/UI/SettingsViewModel.swift, SimplePush/SimplePush/UI/UserViewModel.swift, SimplePushKit/SimplePushKit/Networking/RequestResponseSession.swift.

Architecture takeaways

• SimplePushApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches SimplePushKit, SwiftUI, Network, UIKit 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