Adding support for custom accessibility actions on iOS.

Summary:
This feature has been requested by customers.  Our previous (pre-react) application had support for custom accessibility actions.

This feature allows UI elements to provide a list of custom actions that can be read when VoiceOver is enabled.  UI elements expose one accessibility action by default.  Some UI elements may support multiple actions though other mechanisms like tap and hold.  To expose these actions in an accessible way iOS provides custom accessibility actions.

Feature was tested in the iOS simulator using the Accessibility Inspector.  Custom actions were added to a button and observed in the tool.  Custom actions were also invoked using the tool and then stepped through in the debugger.

The feature was also tested on an iPhone.  VoiceOver was enabled on the device and custom actions were observed for controls that exposed them.

We have been using this feature in our app for some time as well.

[IOS] [ENHANCEMENT] [Accessibility] - Added support for custom accessibility actions

Eric Davison
Microsoft Corp.
Closes #17020

Differential Revision: D6472283

Pulled By: shergin

fbshipit-source-id: 4ac4697dca07028e87ffe71b70c00280e7f2043c

Libraries/Components/View/ReactNativeViewAttributes.js

@@ -18,6 +18,7 @@ var ReactNativeViewAttributes = {};
 ReactNativeViewAttributes.UIView = {
   pointerEvents: true,
   accessible: true,
+  accessibilityActions: true,
   accessibilityLabel: true,
   accessibilityComponentType: true,
   accessibilityLiveRegion: true,
@@ -28,6 +29,7 @@ ReactNativeViewAttributes.UIView = {
   renderToHardwareTextureAndroid: true,
   shouldRasterizeIOS: true,
   onLayout: true,
+  onAccessibilityAction: true,
   onAccessibilityTap: true,
   onMagicTap: true,
   collapsable: true,

Libraries/Components/View/ViewPropTypes.js

@@ -49,11 +49,13 @@ export type ViewLayoutEvent = {
 export type ViewProps = {
   accessible?: bool,
   accessibilityLabel?: React$PropType$Primitive<any>,
+  accessibilityActions?: Array<string>,
   accessibilityComponentType?: AccessibilityComponentType,
   accessibilityLiveRegion?: 'none' | 'polite' | 'assertive',
   importantForAccessibility?: 'auto'| 'yes'| 'no'| 'no-hide-descendants',
   accessibilityTraits?: AccessibilityTrait | Array<AccessibilityTrait>,
   accessibilityViewIsModal?: bool,
+  onAccessibilityAction?: Function,
   onAccessibilityTap?: Function,
   onMagicTap?: Function,
   testID?: string,
@@ -99,6 +101,13 @@ module.exports = {
    */
   accessibilityLabel: PropTypes.node,
 
+  /**
+   * Provides an array of custom actions available for accessibility.
+   *
+   * @platform ios
+   */
+  accessibilityActions: PropTypes.arrayOf(PropTypes.string),
+
   /**
    * Indicates to accessibility services to treat UI component like a
    * native one. Works for Android only.
@@ -165,6 +174,14 @@ module.exports = {
    */
   accessibilityViewIsModal: PropTypes.bool,
 
+  /**
+   * When `accessible` is true, the system will try to invoke this function
+   * when the user performs an accessibility custom action.
+   *
+   * @platform ios
+   */
+  onAccessibilityAction: PropTypes.func,
+
   /**
    * When `accessible` is true, the system will try to invoke this function
    * when the user performs accessibility tap gesture.

React/Views/RCTView.h

@@ -23,9 +23,15 @@
 /**
  * Accessibility event handlers
  */
+@property (nonatomic, copy) RCTDirectEventBlock onAccessibilityAction;
 @property (nonatomic, copy) RCTDirectEventBlock onAccessibilityTap;
 @property (nonatomic, copy) RCTDirectEventBlock onMagicTap;
 
+/**
+ * Accessibility properties
+ */
+@property (nonatomic, copy) NSArray <NSString *> *accessibilityActions;
+
 /**
  * Used to control how touch events are processed.
  */

React/Views/RCTView.m

@@ -156,6 +156,36 @@ - (NSString *)accessibilityLabel
   return RCTRecursiveAccessibilityLabel(self);
 }
 
+- (NSArray <UIAccessibilityCustomAction *> *)accessibilityCustomActions
+{
+  if (!_accessibilityActions.count) {
+    return nil;
+  }
+
+  NSMutableArray *actions = [NSMutableArray array];
+  for (NSString *action in _accessibilityActions) {
+    [actions addObject:[[UIAccessibilityCustomAction alloc] initWithName:action
+                                                                  target:self
+                                                                selector:@selector(didActivateAccessibilityCustomAction:)]];
+  }
+
+  return [actions copy];
+}
+
+- (BOOL)didActivateAccessibilityCustomAction:(UIAccessibilityCustomAction *)action
+{
+  if (!_onAccessibilityAction) {
+    return NO;
+  }
+
+  _onAccessibilityAction(@{
+    @"action": action.name,
+    @"target": self.reactTag
+  });
+
+  return YES;
+}
+
 - (void)setPointerEvents:(RCTPointerEvents)pointerEvents
 {
   _pointerEvents = pointerEvents;

React/Views/RCTViewManager.m

@@ -119,9 +119,11 @@ - (RCTViewManagerUIBlock)uiBlockToAmendWithShadowViewRegistry:(__unused NSDictio
 
 // Acessibility related properties
 RCT_REMAP_VIEW_PROPERTY(accessible, reactAccessibilityElement.isAccessibilityElement, BOOL)
+RCT_REMAP_VIEW_PROPERTY(accessibilityActions, reactAccessibilityElement.accessibilityActions, NSString)
 RCT_REMAP_VIEW_PROPERTY(accessibilityLabel, reactAccessibilityElement.accessibilityLabel, NSString)
 RCT_REMAP_VIEW_PROPERTY(accessibilityTraits, reactAccessibilityElement.accessibilityTraits, UIAccessibilityTraits)
 RCT_REMAP_VIEW_PROPERTY(accessibilityViewIsModal, reactAccessibilityElement.accessibilityViewIsModal, BOOL)
+RCT_REMAP_VIEW_PROPERTY(onAccessibilityAction, reactAccessibilityElement.onAccessibilityAction, RCTDirectEventBlock)
 RCT_REMAP_VIEW_PROPERTY(onAccessibilityTap, reactAccessibilityElement.onAccessibilityTap, RCTDirectEventBlock)
 RCT_REMAP_VIEW_PROPERTY(onMagicTap, reactAccessibilityElement.onMagicTap, RCTDirectEventBlock)
 RCT_REMAP_VIEW_PROPERTY(testID, reactAccessibilityElement.accessibilityIdentifier, NSString)