关闭应用程序后，Xamarin.IOS UILocalNotification.UserInfo为null

Question

本地通知在应用程序打开时应该正常工作。但有些情况下，在关闭申请后本地通知仍留在通知中心。然后单击通知启动应用程序，并在AppDelegate.FinishedLaunching方法中的选项中传递通知数据。选项包含UIApplicationLaunchOptionsLocalNotificationKey键，其值为UIKit.UILocalNotification。此值包含UserInfo属性，该属性应填充通知数据。但是这个UserInfo是null。

另一个问题是当本地通知仍在通知中心并且应用程序重新启动时。单击通知会导致应用程序再次启动并立即停止。

你有这样的问题吗？ Xamarin有问题吗？如何处理这种情况？

创建通知：

public void DisplayNotification(MessageInfo info)
{
    var notificationCenter = UNUserNotificationCenter.Current;

    var content = new UNMutableNotificationContent();
    content.Title = info.Title;
    content.Body = info.Body;
    content.UserInfo = IosStaticMethods.CreateNsDictFromMessageInfo(info);

    UNNotificationTrigger trigger;
    trigger = UNTimeIntervalNotificationTrigger.CreateTrigger(0.1, false);
    var id = (++_LastNotificationId).ToString();
    var request = UNNotificationRequest.FromIdentifier(id, content, trigger);

    notificationCenter.Delegate = new UserNotificationCenterDelegate();

    notificationCenter.AddNotificationRequest(request, (error) =>
    {
        //handle error
    });
}

internal class UserNotificationCenterDelegate : UNUserNotificationCenterDelegate
{
    public override void WillPresentNotification(UNUserNotificationCenter center, UNNotification notification, Action<UNNotificationPresentationOptions> completionHandler)
    {
        completionHandler(UNNotificationPresentationOptions.Alert);
    }

    public override void DidReceiveNotificationResponse(UNUserNotificationCenter center, UNNotificationResponse response, Action completionHandler)
    {
        //do something
    }
}

处理AppDelegate.FinishedLaunching中的通知

if (options != null)
{
    var notification = options["UIApplicationLaunchOptionsLocalNotificationKey"] as UIKit.UILocalNotification;
    var userInfo = notification.UserInfo;//the userInfo is null
}

Answer 1

似乎NSDictionary不应包含NSNull值。删除NSNull值后，即使NSDictionary文档https://developer.apple.com/documentation/foundation/nsdictionary表示允许NSNull，一切都可以。