UIAccessibilityAction informal protocol provides a way for accessibility elements to support specific actions, such as selecting values in a range or scrolling through information on the screen. For example, to respond to a scrolling gesture, you implement the
accessibilityScroll(_:) method and post
UIAccessibilityPageScrolledNotification with the new page status (such as “Page 3 of 9”). Or, to make an element such as a slider or picker view accessible, you first need to characterize it by including the
UIAccessibilityTraitAdjustable trait. Then, you must implement the
accessibilityDecrement() methods. When you do this, assistive technology users can adjust the element using gestures specific to the assistive technology.