Building a feature-rich app for sports analysis

At a glance

Project structure

Source bundle/
└── ActionAndVision/
    ├── GameManager.swift
    ├── AppDelegate.swift
    ├── Common.swift
    ├── SetupViewController.swift
    ├── CameraViewController.swift
    ├── GameViewController.swift
    ├── RootViewController.swift
    ├── SceneDelegate.swift
    ├── SourcePickerViewController.swift
    ├── SummaryViewController.swift
    └── Views/
        ├── BoundingBoxView.swift
        └── DashboardView.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 10 project/configuration file(s) and 41 source declaration(s).

Overall architecture

flowchart LR
    N1["AppDelegate"]
    N2["CameraViewController"]
    N3["GameManager"]
    N4["GameStateChangeObserver"]
    N5["Vision APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4
    N4 --> N5

Reference code

ActionAndVision/AppDelegate.swift:11 — architecture anchor

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    func applicationDidFinishLaunching(_ application: UIApplication) {
        // Warmup Vision pipeline. This needs to be done just once.
        warmUpVisionPipeline()
    }

    // MARK: UISceneSession Lifecycle

    func application(_ application: UIApplication,
                     configurationForConnecting connectingSceneSession: UISceneSession,
                     options: UIScene.ConnectionOptions) -> UISceneConfiguration {
        // Called when a new scene session is being created.
        // Use this method to select a configuration to create the new scene with.
        return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
    }
}

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 Vision.

Ownership and state

classDiagram
    State *-- Array : validNextStates
    ShowSummaryState o-- GKStateMachine : stateMachine
    ShowSummaryState o-- AVAsset : recordedVideoSource
    ShowSummaryState *-- PlayerStats : playerStats

Ownership evidence

ActionAndVision/GameManager.swift:13 — stored dependency or nearest verified ownership anchor

    class State: GKState {
        private(set) var validNextStates: [State.Type]
        // ...
    }

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

ActionAndVision/CameraViewController.swift:18 — representative execution boundary

class CameraViewController: UIViewController {
    // ...
    private let videoDataOutputQueue = DispatchQueue(label: "CameraFeedDataOutput", qos: .userInitiated,
                                                     attributes: [], autoreleaseFrequency: .workItem)
    // ...
}

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

ActionAndVision/GameManager.swift:111 — representative type boundary

protocol GameStateChangeObserver: AnyObject {
    func gameManagerDidEnter(state: GameManager.State, from previousState: GameManager.State?)
}

The source explicitly defines local protocol relationships: BoundingBoxView → AnimatedTransitioning, DashboardView → AnimatedTransitioning, JointSegmentView → AnimatedTransitioning, OverlayLabel → AnimatedTransitioning, ProgressView → AnimatedTransitioning, TrajectoryView → AnimatedTransitioning.

Access control

Reference code

ActionAndVision/CameraViewController.swift:18 — representative boundary

class CameraViewController: UIViewController {
    // ...
    private let videoDataOutputQueue = DispatchQueue(label: "CameraFeedDataOutput", qos: .userInitiated,
                                                     attributes: [], autoreleaseFrequency: .workItem)
    // ...
}

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: Controller: CameraViewController, GameViewController, RootViewController, SetupViewController, SourcePickerViewController; Delegate: AppDelegate, CameraViewControllerOutputDelegate, SceneDelegate; Manager: GameManager; Observer: GameStateChangeObserver; View: BoundingBoxView, CameraFeedView, DashboardView, JointSegmentView, ProgressView.
• Protocols: GameStateChangeObserver, CameraViewControllerOutputDelegate, NormalizedGeometryConverting, AnimatedTransitioning.
• Methods: addValidNextState, isValidNextState, didEnter, reset, gameManagerDidEnter, startObservingStateChanges, stopObservingStateChanges, post.
• Files: ActionAndVision/GameManager.swift, ActionAndVision/AppDelegate.swift, ActionAndVision/SetupViewController.swift, ActionAndVision/CameraViewController.swift, ActionAndVision/GameViewController.swift, ActionAndVision/RootViewController.swift.

Architecture takeaways

• AppDelegate is the main source-visible entry or composition anchor for this sample.
• Framework work reaches UIKit, AVFoundation, Vision, CoreData 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