Developer notes

• A sheet helps people perform a distinct task that’s related to the parent view without taking them away from their current context
• Use native elements when at all possible vs a custom element, as it will handle expected behavior without additional development effort
• Most sheets appear as a card that partially covers the underlying content.
• The screen reader should be confined in the sheet/drawer if it covers underlining content. If a sheet does not cover other content, the screen reader does not have to be confined in it
• Ensure there is a way to collapse or close the sheet for the screen reader (iOS)
• Move screen reader focus into sheet when opened
• A grabber is recommended but not required for Android if a two-finger swipe for the screen reader in any direction closes it

Name

• Name describes the purpose of the control

• iOS Tips
  • Set a label of grabber in Interface Builder in the Identity Inspector
  • setTitle( ) method

  • If no visible label, use accessibilityLabel on control

  • If hiding visible label, use accessibilityLabel on control
• Android Tips
  • android:text XML attribute
  • Optional: use contentDescription for a more descriptive name, depending on type of view and for elements without a visible label
  • contentDescription overrides android:text
  • Use labelFor attribute to connect the visible text label to the control

Role

• iOS
  • UISheetPresentationController
  • Grabber announces as ‘Button”
• Android
  • ModalBottomSheet
  • Grabber announces as “double tap to activate”

Groupings

• Visible label and control are grouped together in one swipe
• Visible label and other non-interactive elements can be grouped together in one swipe in a table row
• iOS
  • accessibilityFrame
  • accessibilityFrameInContainerSpace
  • GroupView
  • Only the container class is an accessible element
• Android
  • ViewGroup
  • Set the container objects android:screenReaderFocusable attribute to true, and each inner object’s android:focusable attribute to false. In doing so, accessibility services can present the inner elements’ contentDescription or names, one after the other, in a single announcement

State

• iOS
  • Grabber announces as expands/collapses
  • Active: isEnabled property
  • Disabled: UIAccessibilityTraitNotEnabled. Announcement: dimmed
• Android
  • Grabber, if any, announces as expands/collapses
  • Active: android:enabled=true
  • Disabled: android:enabled=false. Announcement: disabled

Focus

• Only manage focus when needed. Primarily, let the device manage default focus
• Consider how focus should be managed between child elements and their parent views

• Moving focus into the sheet when a button opens it makes it clear to the screen reader user that there is a sheet available

• iOS
  • accessibilityViewIsModal contains the screen reader focus inside the Modal
  • accessibilityElementIsFocused
  • isAccessibilityElement makes the element visible or not to the Accessibility API
  • accessibilityElementsHidden indicates that the children elements of the target element are visible or not to the Accessibility API
  • To move screen reader focus to newly revealed content: UIAccessibilityLayoutChangedNotification
  • To NOT move focus, but dynamically announce new content: UIAccessibilityAnnouncementNotification
• Android
  • importantForAccessibility makes the element visible to the Accessibility API
  • android:focusable
  • android=clickable
  • Implement an onClick( ) event handler for keyboard, as well as onTouch( )
  • nextFocusDown
  • nextFocusUp
  • nextFocusRight
  • nextFocusLeft
  • accessibilityTraversalBefore (or after)
  • To move screen reader focus to newly revealed content: Type_View_Focused
  • To NOT move focus, but dynamically announce new content: accessibilityLiveRegion(set to polite or assertive)
  • To hide controls: Important_For_Accessibility_false