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

import { 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());
	}
}