Accessibility design for Mac Catalyst

At a glance

Project structure

Source bundle/
├── RoastedBeans/
│   ├── Model/
│   │   ├── RBViewModel.swift
│   │   ├── Coffee.swift
│   │   └── Status.swift
│   ├── AppDelegate.swift
│   ├── RBDetailViewController.swift
│   ├── RBListViewController.swift
│   ├── RBNavigationController.swift
│   ├── RBStatusView.swift
│   ├── SceneDelegate.swift
│   ├── RBCell.swift
│   └── RBImageGrid.swift
└── Configuration/
    └── SampleCode.xcconfig

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 7 project/configuration file(s) and 17 source declaration(s).

Overall architecture

flowchart LR
    N1["AppDelegate"]
    N2["RBDetailViewController"]
    N3["RBViewModel"]
    N4["UIKit / SwiftUI APIs"]
    N1 --> N2
    N2 --> N3
    N3 --> N4

Reference code

RoastedBeans/AppDelegate.swift:9 — architecture anchor

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

        return true
    }

}

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 Accessibility.

Ownership and state

classDiagram
    RBViewModel o-- Coffee : coffee
    RBViewModel o-- Status : status
    RBViewModel *-- Bool : isFavorite
    RBViewModel *-- Array : locationsAvailable

Ownership evidence

RoastedBeans/Model/RBViewModel.swift:12 — stored dependency or nearest verified ownership anchor

struct RBViewModel: Hashable {
    // ...
    var coffee: Coffee
    // ...
}

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.

No source-visible execution, scheduling, or synchronization boundary was found in the indexed source.

@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.

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

RoastedBeans/RBCell.swift:9 — representative type boundary

protocol RBCellActionProtocol: AnyObject {
    func didIncreaseRating(cell: RBCell)
    func didDecreaseRating(cell: RBCell)
    func didToggleFavorite(cell: RBCell)
    func didLongPressCell(cell: RBCell)
}

The source explicitly defines local protocol relationships: RBListViewController → RBCellActionProtocol.

Access control

Reference code

RoastedBeans/RBCell.swift:24 — representative boundary

final class RBCell: UITableViewCell {
    // ...
    @IBOutlet private var rbImageView: UIImageView!
    // ...
}

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: RBDetailViewController, RBListViewController, RBNavigationController; Delegate: AppDelegate, SceneDelegate; View: RBStatusView; ViewModel: RBViewModel.
• Protocols: RBCellActionProtocol.
• Methods: hash, viewModels, application, buildMenu, handleShareMenuAction, viewDidLoad, viewWillAppear, toggleFavorite.
• Files: RoastedBeans/Model/RBViewModel.swift, RoastedBeans/AppDelegate.swift, RoastedBeans/RBDetailViewController.swift, RoastedBeans/RBListViewController.swift, RoastedBeans/RBNavigationController.swift, RoastedBeans/RBStatusView.swift.

Architecture takeaways

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