Accessible Drag and Drop

WWDC 2018

Drag and Drop Refresher

• Interactions are hosted by views
• Starting a drag: UIDragInteration
• Accepting a drop: UIDropInteraction

Accessible Drag and Drop Concepts

• Your accessibility element might not host interactions directly
  - Subviews might host interactions
  - Element might descend from a view that hosts interactions
• Solution
  - Specify logical drags and drops to Accessibility

UIAccessibilityDragging

• Logical drag sources and drop points
  - Drag sources describe where to start drags
  - Drop points describe where to drop
• Users activate drags and drops like custom actions
• Drags and drops often exposed automatically
  - Assigned default name
  - Only interactions in an element’s subtree are exposed
• Allows exposing exactly the interactions that make sense
• Allows specifying a specific name for each
• Implement for the best experience

Exposing an Ancestor’s Drag

Example

• Bar graph built with CALayer
• Drag and drop bar data by dragging the bar itself

UIAccessibilityLocationDescriptor

• Names and describes where to activate an interaction
  - A point
  - In a view
  - With a name

accessibilityDragSourceDescriptors

• Expose drag sources logically associated with the element