Zion

Hi, thanks for the library. I have some trouble when I use ref like this. According to [Refs and the DOM](https://facebook.github.io/react/docs/refs-and-the-dom.html) ```js ref => console.log('ref is ', ref)}>page one page...

// 应用在前台收到通知 + (void)userNotificationCenter:(UNUserNotificationCenter *)center willPresentNotification:(UNNotification *)notification withCompletionHandler:(void (^)(UNNotificationPresentationOptions))completionHandler { NSDictionary * userInfo = notification.request.content.userInfo; if([notification.request.trigger isKindOfClass:[UNPushNotificationTrigger class]]) { [RCTPushNotificationManager didReceiveRemoteNotification:userInfo]; } } 需要加上 `completionHandler(UNNotificationPresentationOptionAlert | UNNotificationPresentationOptionBadge | UNNotificationPresentationOptionSound);`