I have a widget that need to to be refreshed (Reload timeline) every time a calendar changed (EKEventStore changed). How can I achieve this? I am researching on the background task refresh but has no idea how to listen to the notification. func onBackgroundURLSessionEvents(matching matchingString: String, _urlSessionEvent: @escaping ((String, @escaping () -> Void) -> Void)) -> someWidgetConfiguration This func is recommended in Apples's how to keep widget up to date. But cannot understand how to apply this to my case. Thank you for any suggestions.