Mobile Accessibility Testing: Applying WCAG on iOS and Android

Why mobile accessibility matters

WCAG (Web Content Accessibility Guidelines) applies to mobile applications as well as websites. As mobile has grown to represent the majority of digital interactions, the responsibility to make apps usable for people with disabilities has become more important, not less. Blind users, low-vision users, motor-impaired users, and users with cognitive disabilities all use mobile devices and rely on the accessibility features built into iOS and Android.

The legal context reinforces this. The European Accessibility Act requires mobile apps to meet WCAG 2.1 AA from June 2025. In the UK, the Equality Act 2010 applies to mobile products offered to the public.

Screen reader testing: VoiceOver and TalkBack

Screen readers are the most important assistive technology to test on mobile. Blind and low-vision users rely on them to navigate and interact with apps entirely through audio.

VoiceOver (iOS)

VoiceOver is Apple's built-in screen reader. To enable it, go to Settings, then Accessibility, then VoiceOver. Users navigate by swiping right to move forward, swiping left to go back, and double-tapping to activate an element. A three-finger swipe scrolls.

Key things to test with VoiceOver:

• All interactive elements (buttons, links, form inputs) are reachable and have meaningful labels
• Images have accurate alt text via accessibilityLabel
• Decorative images are hidden from VoiceOver
• Custom controls announce their role and state (e.g., "button", "selected", "expanded")
• Modals and alerts interrupt VoiceOver focus correctly and return focus on dismissal
• Dynamic content changes are announced via accessibility notifications

TalkBack (Android)

TalkBack is Android's built-in screen reader, found in Settings under Accessibility. Navigation gestures are similar to VoiceOver but not identical: swipe right or left to navigate, double-tap to activate.

Key things to test with TalkBack:

• All interactive elements have contentDescription or associated labels
• Views marked as unimportant for accessibility are correctly skipped
• Custom views implement the Android Accessibility API correctly
• Focus order follows a logical reading sequence
• Live regions announce dynamic content updates

Touch target sizes

WCAG 2.5.8 (Target Size Minimum, Level AA in WCAG 2.2) requires a minimum touch target size of 24x24 CSS pixels. Apple's Human Interface Guidelines recommend 44x44 points; Google's Material Design recommends 48x48 density-independent pixels.

Small touch targets cause two problems: accidental activations of adjacent elements, and inability to activate the target at all for users with motor impairments. Test target sizes by measuring the tap area in your layout tooling, not just the visual size of the element as rendered.

Colour contrast

The WCAG 2.1 AA requirement for text contrast (4.5:1 for normal text, 3:1 for large text) applies identically to mobile. Dark mode introduces an additional consideration: test contrast in both light and dark mode if your app supports theme switching.

Mobile-specific colour issues to check:

• Text on gradient backgrounds: contrast must pass at all points along the gradient
• Text over images: overlay techniques must ensure sufficient contrast regardless of image content
• Status indicators that rely on colour alone without supporting text or iconography

Text scaling

Both iOS (Dynamic Type) and Android (Font Scale) allow users to increase system font sizes, up to 310% on some settings. Apps must support font scaling without text being clipped, overlapping, or becoming unreadable.

Test at the maximum system font size and verify:

• Text does not overflow its container or get clipped
• Buttons and labels remain fully visible
• Scrollable views allow all content to be read
• Layouts reflow rather than truncate

Focus order and switch access

Focus order matters for screen reader users and users of switch access controls (physical switch devices used by users with motor impairments). Focus should follow the visual reading order of the screen: typically top-to-bottom, left-to-right.

When testing with VoiceOver or TalkBack, swipe through the screen and verify the focus sequence is logical, covers all interactive elements, and does not visit decorative content.

Testing tools for mobile accessibility

• Accessibility Inspector (macOS/Xcode): Apple's desktop tool for inspecting accessibility properties of iOS simulators. Can run automated audits and highlight accessibility failures.
• Accessibility Scanner (Android): Google's app that overlays suggestions on any screen, highlighting small touch targets, low contrast, and missing labels
• axe DevTools Mobile: an automated mobile accessibility testing tool that integrates with Appium for CI pipeline testing
• VoiceOver and TalkBack directly: no automated tool replaces manual testing with the actual screen readers your users will use

Common mobile accessibility failures

The most frequently found issues in mobile accessibility audits:

• Icon-only buttons with no accessible label
• Custom bottom sheets and modals that do not trap screen reader focus
• Form fields without associated labels
• Images used as buttons without accessibilityLabel
• Toast notifications that appear and disappear without being announced to screen readers
• Colour-only status indicators
• Text truncated at standard sizes when system font scaling is applied

Need mobile accessibility testing? See our Mobile App Testing service or our Accessibility Testing service.

Related reading: How to Test a Mobile App: iOS and Android Guide