iOS Accessibility — SwiftUI and UIKit

Every user-facing view must be usable with VoiceOver, Switch Control, Voice Control, Full Keyboard Access, and other assistive technologies. This skill covers the patterns and APIs required to build accessible iOS apps.

Contents

• Core Principles
• How VoiceOver Reads Elements
• SwiftUI Accessibility Modifiers
• Focus Management
• Dynamic Type
• Custom Rotors
• System Accessibility Preferences
• Decorative Content
• Assistive Access (iOS 18+)
• UIKit Accessibility Patterns
• Accessibility Custom Content
• Testing Accessibility
• Common Mistakes
• Review Checklist
• References

Core Principles

1. Every interactive element MUST have an accessible label. If no visible text exists, add .accessibilityLabel.
2. Every custom control MUST have correct traits via .accessibilityAddTraits (never direct assignment).
3. Decorative images MUST be hidden from assistive technologies.
4. Sheet and dialog dismissals MUST return VoiceOver focus to the trigger element.
5. All tap targets MUST be at least 44x44 points.
6. Dynamic Type MUST be supported everywhere (system fonts, @ScaledMetric, adaptive layouts).
7. No information conveyed by color alone -- always provide text or icon alternatives.
8. System accessibility preferences MUST be respected: Reduce Motion, Reduce Transparency, Bold Text, Increase Contrast.

How VoiceOver Reads Elements

VoiceOver reads element properties in a fixed, non-configurable order:

Label -> Value -> Trait -> Hint

Design your labels, values, and hints with this reading order in mind.

SwiftUI Accessibility Modifiers

See references/a11y-patterns.md for detailed SwiftUI modifier examples (labels, hints, traits, grouping, custom controls, adjustable actions, and custom actions).

Focus Management

Focus management is where most apps fail. When a sheet, alert, or popover is dismissed, VoiceOver focus MUST return to the element that triggered it.

@AccessibilityFocusState (iOS 15+)

@AccessibilityFocusState is a property wrapper that reads and writes the current accessibility focus. It works with Bool for single-target focus or an optional Hashable enum for multi-target focus.

struct ContentView: View {
    @State private var showSheet = false
    @AccessibilityFocusState private var focusOnTrigger: Bool

    var body: some View {
        Button("Open Settings") { showSheet = true }
            .accessibilityFocused($focusOnTrigger)
            .sheet(isPresented: $showSheet) {
                SettingsSheet()
                    .onDisappear {
                        // Slight delay allows the transition to complete before moving focus
                        Task { @MainActor in
                            try? await Task.sleep(for: .milliseconds(100))
                            focusOnTrigger = true
                        }
                    }
            }
    }
}

Multi-Target Focus with Enum

enum A11yFocus: Hashable {
    case nameField
    case emailField
    case submitButton
}

struct FormView: View {
    @AccessibilityFocusState private var focus: A11yFocus?

    var body: some View {
        Form {
            TextField("Name", text: $name)
                .accessibilityFocused($focus, equals: .nameField)
            TextField("Email", text: $email)
                .accessibilityFocused($focus, equals: .emailField)
            Button("Submit") { validate() }
                .accessibilityFocused($focus, equals: .submitButton)
        }
    }

    func validate() {
        if name.isEmpty {
            focus = .nameField // Move VoiceOver to the invalid field
        }
    }
}

Custom Modals

Custom overlay views need the .isModal trait to trap VoiceOver focus and an escape action for dismissal:

CustomDialog()
    .accessibilityAddTraits(.isModal)
    .accessibilityAction(.escape) { dismiss() }

Accessibility Notifications (UIKit)

When you need to announce changes or move focus imperatively in UIKit contexts:

// Announce a status change (e.g., "Item deleted", "Upload complete")
UIAccessibility.post(notification: .announcement, argument: "Upload complete")

// Partial screen update -- move focus to a specific element
UIAccessibility.post(notification: .layoutChanged, argument: targetView)

// Full screen transition -- move focus to the new screen
UIAccessibility.post(notification: .screenChanged, argument: newScreenView)

Dynamic Type

See references/a11y-patterns.md for Dynamic Type and adaptive layout examples, including @ScaledMetric and minimum tap target patterns.

Custom Rotors

Rotors let VoiceOver users quickly navigate to specific content types. Add custom rotors for content-heavy screens. See references/a11y-patterns.md for complete rotor examples.

System Accessibility Preferences

Always respect these environment values:

@Environment(\.accessibilityReduceMotion) var reduceMotion
@Environment(\.accessibilityReduceTransparency) var reduceTransparency
@Environment(\.colorSchemeContrast) var contrast         // .standard or .increased
@Environment(\.legibilityWeight) var legibilityWeight    // .regular or .bold

Reduce Motion

Replace movement-based animations with crossfades or no animation:

withAnimation(reduceMotion ? nil : .spring()) {
    showContent.toggle()
}
content.transition(reduceMotion ? .opacity : .slide)

Reduce Transparency, Increase Contrast, Bold Text

// Solid backgrounds when transparency is reduced
.background(reduceTransparency ? Color(.systemBackground) : Color(.systemBackground).opacity(0.85))

// Stronger colors when contrast is increased
.foregroundStyle(contrast == .increased ? .primary : .secondary)

// Bold weight when system bold text is enabled
.fontWeight(legibilityWeight == .bold ? .bold : .regular)

Decorative Content

// Decorative images: hidden from VoiceOver
Image(decorative: "background-pattern")
Image("visual-divider").accessibilityHidden(true)

// Icon next to text: Label handles this automatically
Label("Settings", systemImage: "gear")

// Icon-only buttons: MUST have an accessibility label
Button<