Building and testing a Safari web extension

At a glance

Project structure

Source bundle/
└── ShinyOnTrack/
    ├── Xcode Project/
    │   ├── iOS (App)/
    │   │   ├── AppDelegate.swift
    │   │   └── SceneDelegate.swift
    │   ├── macOS (App)/
    │   │   └── AppDelegate.swift
    │   ├── Shared (App)/
    │   │   └── ViewController.swift
    │   └── Shared (Extension)/
    │       └── SafariWebExtensionHandler.swift
    └── Resources/
        ├── background.js
        ├── blocked.js
        ├── content.js
        ├── options.js
        └── utilities/
            ├── host.js
            ├── rules.js
            └── scripting.js

Structure observations

• Architecturally prominent files are ranked from entry points and role-named declarations; resource-only paths are omitted.
• Primary languages: JavaScript, Swift.
• The verified tree contains 10 project/configuration file(s) and 5 source declaration(s).

Overall architecture

flowchart LR
    N1["AppDelegate"]
    N2["ViewController"]
    N3["SafariWebExtensionHandler"]
    N4["SafariServices APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4

Reference code

ShinyOnTrack/Xcode Project/iOS (App)/AppDelegate.swift:10 — architecture anchor

@main
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // The override point for customization after the app launches.
        return true
    }

    func application(
        _ application: UIApplication,
        configurationForConnecting connectingSceneSession: UISceneSession,
        options: UIScene.ConnectionOptions
    ) -> UISceneConfiguration {
        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 Safari Services.

Ownership and state

classDiagram
    AppDelegate o-- UIWindow : window
    ViewController o-- WKWebView : webView
    SceneDelegate o-- UIWindow : window

Ownership evidence

ShinyOnTrack/Xcode Project/iOS (App)/AppDelegate.swift:13 — stored dependency or nearest verified ownership anchor

@main
class AppDelegate: UIResponder, UIApplicationDelegate {
    // ...
    var window: UIWindow?
    // ...
}

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

ShinyOnTrack/Xcode Project/Shared (App)/ViewController.swift:51 — representative execution boundary

#if os(iOS)
// ...
#elseif os(macOS)
            DispatchQueue.main.async {
              webView.evaluateJavaScript("show('mac', \(state.isEnabled))")
            }
#endif

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

ShinyOnTrack/Xcode Project/iOS (App)/AppDelegate.swift:11 — representative type boundary

@main
class AppDelegate: UIResponder, UIApplicationDelegate {
    // ...
    var window: UIWindow?
    // ...
}

No local protocol conformance is claimed as protocol-oriented design; external framework conformances are listed only as dependencies.

Access control

Reference code

ShinyOnTrack/Xcode Project/Shared (Extension)/SafariWebExtensionHandler.swift:36 — representative boundary

  private func reply(context: NSExtensionContext, success: Bool) {
    let response = NSExtensionItem()
    response.userInfo = [SFExtensionMessageKey: ["success": success]]
    context.completeRequest(returningItems: [response], completionHandler: nil)
  }

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: ViewController; Delegate: AppDelegate, SceneDelegate; Handler: SafariWebExtensionHandler.
• Protocols: no local protocol declaration in the scanned source.
• Methods: application, applicationDidFinishLaunching, applicationShouldTerminateAfterLastWindowClosed, viewDidLoad, webView, userContentController, beginRequest, reply.
• Files: ShinyOnTrack/Xcode Project/iOS (App)/AppDelegate.swift, ShinyOnTrack/Xcode Project/macOS (App)/AppDelegate.swift, ShinyOnTrack/Xcode Project/Shared (App)/ViewController.swift, ShinyOnTrack/Xcode Project/Shared (Extension)/SafariWebExtensionHandler.swift, ShinyOnTrack/Xcode Project/iOS (App)/SceneDelegate.swift.

Architecture takeaways

• AppDelegate is the main source-visible entry or composition anchor for this sample.
• Framework work reaches UIKit, Cocoa, SafariServices, LocalAuthentication 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