feat(core): first class a11y support (#8909)

packages/core/accessibility/accessibility-service.ios.ts

@@ -0,0 +1,75 @@
+import * as Application from '../application';
+import { Observable } from '../data/observable';
+import { Trace } from '../trace';
+import { AccessibilityServiceEnabledPropName, CommonA11YServiceEnabledObservable, SharedA11YObservable } from './accessibility-service-common';
+
+export function isAccessibilityServiceEnabled(): boolean {
+	return getSharedA11YObservable().accessibilityServiceEnabled;
+}
+
+export function getAndroidAccessibilityManager(): null {
+	return null;
+}
+
+let sharedA11YObservable: SharedA11YObservable;
+let nativeObserver;
+
+function getSharedA11YObservable(): SharedA11YObservable {
+	if (sharedA11YObservable) {
+		return sharedA11YObservable;
+	}
+
+	sharedA11YObservable = new SharedA11YObservable();
+
+	let isVoiceOverRunning: () => boolean;
+	if (typeof UIAccessibilityIsVoiceOverRunning === 'function') {
+		isVoiceOverRunning = UIAccessibilityIsVoiceOverRunning;
+	} else {
+		if (typeof UIAccessibilityIsVoiceOverRunning !== 'function') {
+			Trace.write(`UIAccessibilityIsVoiceOverRunning() - is not a function`, Trace.categories.Accessibility, Trace.messageType.error);
+
+			isVoiceOverRunning = () => false;
+		}
+	}
+
+	sharedA11YObservable.set(AccessibilityServiceEnabledPropName, isVoiceOverRunning());
+
+	let voiceOverStatusChangedNotificationName: string | null = null;
+	if (typeof UIAccessibilityVoiceOverStatusDidChangeNotification !== 'undefined') {
+		// iOS 11+
+		voiceOverStatusChangedNotificationName = UIAccessibilityVoiceOverStatusDidChangeNotification;
+	} else if (typeof UIAccessibilityVoiceOverStatusChanged !== 'undefined') {
+		// iOS <11
+		voiceOverStatusChangedNotificationName = UIAccessibilityVoiceOverStatusChanged;
+	}
+
+	if (voiceOverStatusChangedNotificationName) {
+		nativeObserver = Application.ios.addNotificationObserver(voiceOverStatusChangedNotificationName, () => {
+			sharedA11YObservable?.set(AccessibilityServiceEnabledPropName, isVoiceOverRunning());
+		});
+
+		Application.on(Application.exitEvent, () => {
+			if (nativeObserver) {
+				Application.ios.removeNotificationObserver(nativeObserver, voiceOverStatusChangedNotificationName);
+			}
+
+			nativeObserver = null;
+
+			if (sharedA11YObservable) {
+				sharedA11YObservable.removeEventListener(Observable.propertyChangeEvent);
+
+				sharedA11YObservable = null;
+			}
+		});
+	}
+
+	Application.on(Application.resumeEvent, () => sharedA11YObservable.set(AccessibilityServiceEnabledPropName, isVoiceOverRunning()));
+
+	return sharedA11YObservable;
+}
+
+export class AccessibilityServiceEnabledObservable extends CommonA11YServiceEnabledObservable {
+	constructor() {
+		super(getSharedA11YObservable());
+	}
+}