iOS: Introduce API for making screen reader announcements

Libraries/Components/AccessibilityInfo/AccessibilityInfo.ios.js

@@ -18,9 +18,11 @@ var RCTDeviceEventEmitter = require('RCTDeviceEventEmitter');
 var AccessibilityManager = NativeModules.AccessibilityManager;
 
 var VOICE_OVER_EVENT = 'voiceOverDidChange';
+var ANNOUNCEMENT_DID_FINISH_EVENT = 'announcementDidFinish';
 
 type ChangeEventName = $Enum<{
   change: string,
+  announcementFinished: string
 }>;
 
 var _subscriptions = new Map();
@@ -97,15 +99,30 @@ var AccessibilityInfo = {
    * - `change`: Fires when the state of the screen reader changes. The argument
    *   to the event handler is a boolean. The boolean is `true` when a screen
    *   reader is enabled and `false` otherwise.
+   * - `announcementFinished`: iOS-only event. Fires when the screen reader has
+   *   finished making an announcement. The argument to the event handler is a dictionary
+   *   with these keys:
+   *     - `announcement`: The string announced by the screen reader.
+   *     - `success`: A boolean indicating whether the announcement was successfully made.
    */
   addEventListener: function (
     eventName: ChangeEventName,
     handler: Function
   ): Object {
-    var listener = RCTDeviceEventEmitter.addListener(
-      VOICE_OVER_EVENT,
-      handler
-    );
+    var listener;
+
+    if (eventName === 'change') {
+      listener = RCTDeviceEventEmitter.addListener(
+        VOICE_OVER_EVENT,
+        handler
+      );
+    } else if (eventName === 'announcementFinished') {
+      listener = RCTDeviceEventEmitter.addListener(
+        ANNOUNCEMENT_DID_FINISH_EVENT,
+        handler
+      );
+    }
+
     _subscriptions.set(handler, listener);
     return {
       remove: AccessibilityInfo.removeEventListener.bind(null, eventName, handler),
@@ -121,6 +138,15 @@ var AccessibilityInfo = {
     AccessibilityManager.setAccessibilityFocus(reactTag);
   },
 
+  /**
+   * iOS-Only. Post a string to be announced by the screen reader.
+   */
+  announceForAccessibility: function(
+    announcement: string
+  ): void {
+    AccessibilityManager.announceForAccessibility(announcement);
+  },
+
   /**
    * Remove an event handler.
    */

React/Modules/RCTAccessibilityManager.m

@@ -71,6 +71,11 @@ - (instancetype)init
                                              selector:@selector(didReceiveNewVoiceOverStatus:)
                                                  name:UIAccessibilityVoiceOverStatusChanged
                                                object:nil];
+
+    [[NSNotificationCenter defaultCenter] addObserver:self
+                                             selector:@selector(accessibilityAnnouncementDidFinish:)
+                                                 name:UIAccessibilityAnnouncementDidFinishNotification
+                                               object:nil];
 
     self.contentSizeCategory = RCTSharedApplication().preferredContentSizeCategory;
     _isVoiceOverEnabled = UIAccessibilityIsVoiceOverRunning();
@@ -101,6 +106,20 @@ - (void)didReceiveNewVoiceOverStatus:(__unused NSNotification *)notification
   }
 }
 
+- (void)accessibilityAnnouncementDidFinish:(__unused NSNotification *)notification
+{
+  NSDictionary *userInfo = notification.userInfo;
+  // Response dictionary to populate the event with.
+  NSDictionary *response = @{@"announcement": userInfo[UIAccessibilityAnnouncementKeyStringValue],
+                              @"success": userInfo[UIAccessibilityAnnouncementKeyWasSuccessful]};
+
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
+  [_bridge.eventDispatcher sendDeviceEventWithName:@"announcementDidFinish"
+                                              body:response];
+#pragma clang diagnostic pop
+}
+
 - (void)setContentSizeCategory:(NSString *)contentSizeCategory
 {
   if (_contentSizeCategory != contentSizeCategory) {
@@ -171,6 +190,11 @@ - (void)setMultipliers:(NSDictionary<NSString *, NSNumber *> *)multipliers
   });
 }
 
+RCT_EXPORT_METHOD(announceForAccessibility:(NSString *)announcement)
+{
+  UIAccessibilityPostNotification(UIAccessibilityAnnouncementNotification, announcement);
+}
+
 RCT_EXPORT_METHOD(getMultiplier:(RCTResponseSenderBlock)callback)
 {
   if (callback) {