Building a cross-platform web browser

At a glance

Project structure

Source bundle/
└── WebKitForSwiftUI/
    └── WebKitForSwiftUI/
        ├── WebKitForSwiftUIApp.swift
        ├── Models/
        │   ├── BrowserManager.swift
        │   └── FavoriteWebpage.swift
        ├── Browser/
        │   ├── BrowserView.swift
        │   ├── AddressBar.swift
        │   └── BrowserToolbar.swift
        ├── ContentView.swift
        └── Favorites/
            ├── FavoriteListView.swift
            ├── FavoriteRowView.swift
            ├── EditFavoriteSheet.swift
            ├── FavoriteContextMenu.swift
            └── FavoriteToolbar.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 3 project/configuration file(s) and 17 source declaration(s).

Overall architecture

flowchart LR
    N1["WebKitForSwiftUIApp"]
    N2["ContentView"]
    N3["BrowserManager"]
    N4["CustomSchemeHandler"]
    N5["WebKit APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4
    N4 --> N5

Reference code

WebKitForSwiftUI/WebKitForSwiftUI/WebKitForSwiftUIApp.swift:11 — architecture anchor

@main
struct WebKitForSwiftUIApp: App {
    @FocusedValue(BrowserManager.self) var manager
    // ...
}

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 WebKit.

Ownership and state

classDiagram
    BrowserManager o-- WebPage : page
    BrowserManager *-- Bool : privateBrowsingEnabled
    BrowserManager *-- String : displayUrl
    BrowserManager o-- UserInterfaceSizeClass : horizontalSizeClass

Ownership evidence

WebKitForSwiftUI/WebKitForSwiftUI/Models/BrowserManager.swift:14 — stored dependency or nearest verified ownership anchor

@Observable
class BrowserManager {
    let page: WebPage
    // ...
}

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

WebKitForSwiftUI/WebKitForSwiftUI/Browser/BrowserView.swift:60 — representative execution boundary

                        for try await event in browserManager.page.navigations {
                            print(event)
                        }

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

WebKitForSwiftUI/WebKitForSwiftUI/WebKitForSwiftUIApp.swift:12 — representative type boundary

@main
struct WebKitForSwiftUIApp: App {
    @FocusedValue(BrowserManager.self) var manager
    // ...
}

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

Access control

Reference code

WebKitForSwiftUI/WebKitForSwiftUI/Browser/AddressBar.swift:13 — representative boundary

struct AddressFieldAndIcon: View {
    @Environment(BrowserManager.self) private var browserManager
    // ...
}

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: WebKitForSwiftUIApp; Handler: CustomSchemeHandler, NavigationPolicyHandler; Manager: BrowserManager; View: BrowserView, ContentView, FavoriteListView, FavoriteRowView.
• Protocols: no local protocol declaration in the scanned source.
• Methods: deleteItem, navigateTo, addProtocolIfNecessary, copyToPasteboard, openURL, addFavorite, editItem, makeFavorite.
• Files: WebKitForSwiftUI/WebKitForSwiftUI/WebKitForSwiftUIApp.swift, WebKitForSwiftUI/WebKitForSwiftUI/Models/BrowserManager.swift, WebKitForSwiftUI/WebKitForSwiftUI/Browser/BrowserView.swift, WebKitForSwiftUI/WebKitForSwiftUI/ContentView.swift, WebKitForSwiftUI/WebKitForSwiftUI/Favorites/FavoriteListView.swift, WebKitForSwiftUI/WebKitForSwiftUI/Favorites/FavoriteRowView.swift.

Architecture takeaways

• WebKitForSwiftUIApp is the main source-visible entry or composition anchor for this sample.
• Framework work reaches SwiftUI, WebKit, UniformTypeIdentifiers, LinkPresentation 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