Integrating accessibility into your app

At a glance

Project structure

Source bundle/
└── AccessibilityUIExamples/
    ├── Application/
    │   ├── AppDelegate.swift
    │   └── MainViewController.swift
    ├── LayoutArea/
    │   └── CustomLayoutAreaView.swift
    ├── RadioButtons/
    │   └── CustomRadioButtonsView.swift
    ├── Stepper/
    │   └── CustomStepperView.swift
    ├── Switches/
    │   └── TwoPositionSwitchView.swift
    ├── Checkbox/
    │   ├── CustomCheckBoxView.m
    │   └── CustomCheckBoxView.swift
    ├── CustomRotors/
    │   ├── ElementView/
    │   │   └── CustomRotorsContainerView.swift
    │   └── TextView/
    │       └── CustomRotorsTextView.swift
    ├── Images/
    │   └── ImageViewLayerView.swift
    └── Outline/
        └── CustomOutlineView.m

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, Metal, Objective-C, Swift.
• The verified tree contains 29 project/configuration file(s) and 85 source declaration(s).

Overall architecture

flowchart LR
    N1["AppDelegate"]
    N2["ButtonBaseViewController"]
    N3["Cocoa / simd APIs"]
    N1 --> N2
    N2 --> N3

Reference code

AccessibilityUIExamples/Application/AppDelegate.swift:10 — architecture anchor

@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {

}

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
    LayoutInfo *-- CGFloat : LayoutItemHandleSize
    LayoutInfo *-- CGFloat : LayoutItemMinSize
    LayoutInfo *-- CGFloat : LayoutItemMoveDelta
    LayoutInfo *-- CGFloat : LayoutItemSize

Ownership evidence

AccessibilityUIExamples/LayoutArea/CustomLayoutAreaView.swift:23 — stored dependency or nearest verified ownership anchor

    struct LayoutInfo {
        static let LayoutItemHandleSize = CGFloat(8.0)
        static let LayoutItemMinSize = CGFloat(LayoutItemHandleSize * 3.0)
        static let LayoutItemMoveDelta = CGFloat(10.0)
        static let LayoutItemSize = CGFloat(50.0)
    }

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

AccessibilityUIExamples/Buttons/CustomButtonView.swift:77 — representative execution boundary

        DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + delay, execute: {
            onCompletion()
        })

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

AccessibilityUIExamples/Application/MainViewController.swift:264 — representative type boundary

protocol MainViewControllerDelegate: AnyObject {
    func didChangeExampleSelection(mainViewController: MainViewController, selection: Example?)
}

The source explicitly defines local protocol relationships: SplitViewController → MainViewControllerDelegate, CustomSearchFieldViewController → SharedFocusSearchFieldDelegate.

Access control

Reference code

AccessibilityUIExamples/Application/MainViewController.swift:62 — representative boundary

    public func numberOfRows(in tableView: NSTableView) -> Int {
        return (examplesArrayController.arrangedObjects as AnyObject).count
    }

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: ButtonBaseViewController, ButtonSubclassViewController, ButtonViewController, ButtonViewSubclassViewController, ButtonWithImageViewController; Delegate: AppDelegate, CustomRotorsElementViewDelegate, CustomRotorsTextViewDelegate, MainViewControllerDelegate, SharedFocusSearchFieldDelegate; View: CoreTextColumnView, CoreTextView, CustomButtonView, CustomCheckBoxView, CustomLayoutAreaView.
• Protocols: MainViewControllerDelegate, CustomRotorsElementViewDelegate, CustomRotorsTextViewDelegate, SharedFocusSearchFieldDelegate.
• Methods: commonInit, layoutItemsInZOrder, bringItemToTop, handleArrowKeys, keyDown, hitTestForLayoutItemAtPoint, hitTestForHandleAtPoint, mouseDown.
• Files: AccessibilityUIExamples/Application/AppDelegate.swift, AccessibilityUIExamples/LayoutArea/CustomLayoutAreaView.swift, AccessibilityUIExamples/RadioButtons/CustomRadioButtonsView.swift, AccessibilityUIExamples/Stepper/CustomStepperView.swift, AccessibilityUIExamples/Switches/TwoPositionSwitchView.swift, AccessibilityUIExamples/Application/MainViewController.swift.

Architecture takeaways

• AppDelegate is the main source-visible entry or composition anchor for this sample.
• Framework work reaches Cocoa, simd, CoreText, MediaLibrary 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