在xamarin IOS中处理推送通知时，使用DidReceiveRemoteNotification处理程序，它可以在前台和后台随机工作。

有时我会收到通知，有时却不会。

我们正在使用Xamarin.IOS 13.4。

这是我们的AppDeletage.cs代码：

    [Register("AppDelegate")]
    public class AppDelegate : FormsApplicationDelegate,IUNUserNotificationCenterDelegate,IMessagingDelegate
    {
        public override bool Finishedlaunching(UIApplication app,NSDictionary options)
        {
            RegistrarNotificacionesRemotas();
            LoadApplication(new App());
            App.ConfigNotificationEvents();

            return base.Finishedlaunching(app,options);
        }

        public override void RegisteredForRemoteNotifications(UIApplication application,NSData devicetoken)
        {
           App.SendRegistrationToServer(devicetoken.ToString(),(int)Plataforma.iOS);
        }

        public override void ReceivedRemoteNotification(UIApplication application,NSDictionary userInfo)
        {


        }


        public override void DidReceiveRemoteNotification(UIApplication application,NSDictionary userInfo,action<UIBackgroundFetchResult> completionHandler)
        {

        }

        private void RegistrarNotificacionesRemotas()
        {
            Firebase.Core.App.Configure();
            // Register your app for remote notifications.
            if (UIDevice.CurrentDevice.CheckSystemVersion(10,0))
            {

                // For iOS 10 display notification (sent via APNS)
                UNUserNotificationCenter.Current.Delegate = this;

                var authOptions = UNAuthorizationOptions.Alert | UNAuthorizationOptions.Badge | UNAuthorizationOptions.Sound;
                UNUserNotificationCenter.Current.RequestAuthorization(authOptions,(granted,error) => {
                    Console.WriteLine(granted);
                });
            }
            else
            {
                // iOS 9 or before
                var allNotificationTypes = UIUserNotificationType.Alert | UIUserNotificationType.Badge | UIUserNotificationType.Sound;
                var settings = UIUserNotificationSettings.GetSettingsForTypes(allNotificationTypes,null);
                UIApplication.SharedApplication.RegisterUserNotificationSettings(settings);
            }

            UIApplication.SharedApplication.RegisterForRemoteNotifications();
            Messaging.SharedInstance.Delegate = this;
            Messaging.SharedInstance.ShouldEstablishDirectChannel = true;
        }

    }
}

在前台，一切都很好，但是在后台永远不会触发方法ReceivedRemoteNotification或DidReceiveRemoteNotification