UIAccessibilityAction Protocol Reference

(informal protocol)

Adopted by	NSObject
Framework	/System/Library/Frameworks/UIKit.framework
Companion guide	Accessibility Programming Guide for iOS
Declared in	UIAccessibility.h

Overview

The 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 accessibilityIncrement and accessibilityDecrement methods. When you do this, assistive technology users can adjust the element using gestures specific to the assistive technology.

Tasks

Performing an Action

Instance Methods

accessibilityDecrement

Adjusts the accessibility element so that its content is decreased.

- (void)accessibilityDecrement

Availability

Available in iOS 4.0 and later.

Declared In

UIAccessibility.h

accessibilityIncrement

Adjusts the accessibility element so that its content is increased.

- (void)accessibilityIncrement

Availability

Available in iOS 4.0 and later.

Declared In

UIAccessibility.h

accessibilityPerformEscape

Dismisses a modal view and returns the success or failure of the action.

- (BOOL)accessibilityPerformEscape

Return Value

YES if the modal view is successfully dismissed; otherwise, NO. By default, this method returns NO.

Discussion

Implement this method on an element or containing view that can be revealed modally or in a hierarchy. When a VoiceOver user performs a dismiss action, this method dismisses the view. For example, you might implement this method for a popover in order to give users a deliberate dismiss action to perform that closes the popover.

Availability

Available in iOS 5.0 and later.

Declared In

UIAccessibility.h

accessibilityPerformMagicTap

Performs a salient action.

- (BOOL)accessibilityPerformMagicTap

Return Value

YES if the magic tap action succeeds; otherwise, NO. By default, this method returns NO.

Discussion

The exact action performed by this method depends your app, typically toggling the most important state of the app. For example, in the Phone app it answers and ends phone calls, in the Music app it plays and pauses playback, in the Clock app it starts and stops a timer, and in the Camera app it takes a picture.

Availability

Available in iOS 6.0 and later.

Declared In

UIAccessibility.h

accessibilityScroll:

Scrolls screen content in an application-specific way and returns the success or failure of the action.

- (BOOL)accessibilityScroll:(UIAccessibilityScrollDirection)direction

Parameters

direction: A constant that specifies the direction of the scrolling action. See Scroll Directions for descriptions of valid constants.

Return Value

YES if the scrolling action succeeds; otherwise, NO. By default, this method returns NO.

Discussion

Implement this method if a view in the view hierarchy supports a scroll by page action.

If the scrolling action succeeds for the specified direction, return YES and post the UIAccessibilityPageScrolledNotification notification.
If the scrolling action fails, accessibilityScroll: is called on a parent view in the hierarchy.

Availability

Available in iOS 4.2 and later.

Declared In

UIAccessibility.h

Constants

UIAccessibilityScrollDirection

The direction of a scrolling action.

typedef enum {
   UIAccessibilityScrollDirectionRight = 1,
   UIAccessibilityScrollDirectionLeft,
   UIAccessibilityScrollDirectionUp,
   UIAccessibilityScrollDirectionDown,
   UIAccessibilityScrollDirectionNext,
   UIAccessibilityScrollDirectionPrevious
} UIAccessibilityScrollDirection;