swift - Calendar changed Mac -

i making program runs in background , needs know wether user added events calendar app (the standard app) in mac os. tried using ekeventstorechanged notification, doesn't seem fired when there changes. code notification this:

func applicationdidfinishlaunching(_ anotification: notification) {      notificationcenter.default.addobserver(self, selector: #selector(calendarchanged), name:  nsnotification.name.ekeventstorechanged  , object: nil) }  func calendarchanged(notificatie : nsnotification) {     print ("something changed") } 

is possible receive notifications changes calendar way? or should try other approach?