Deleting reminders from calendar in Swift

问题:

I use the following function to retrieve my calendar:

func retrieveCalendar() -> EKCalendar? {

    appDelegate = UIApplication.sharedApplication().delegate
        as? AppDelegate

    var myCalendar:  EKCalendar?
    let calendars = appDelegate!.eventStore!.calendarsForEntityType(EKEntityTypeReminder) as! [EKCalendar]
    let filteredCalendars = calendars.filter {$0.title == "MedicalCalendar"}
    if filteredCalendars.isEmpty {
        println("could not find reminder calendar 'MedicalCalendar'")
        return nil
    } else {
        myCalendar = filteredCalendars[0]
        return myCalendar!
    }

}

However, anytime I add new events to the calendar I'd like to check if they already exist there. I figured out that the easiest approach would be to delete all reminders and load new ones again. I tried:

self.retrieveCalendar()?.reset()

But it does not work. How can I remove reminders from calendar?(either one at a time or all of them at once)

回答1:

To check reminders you have to call the method fetchRemindersMatchingPredicate() in conjunction with predicateForRemindersInCalendars or predicateForIncompleteRemindersWithDueDateStarting:ending:calendars: or predicateForCompletedRemindersWithCompletionDateStarting:ending:calendars:

For example if you want to delete all expired reminders in the past until now, use something like this

• assumed properties:

  var calendar : EKCalendar // current calendar
  let eventStore : EKEventStore // current event store
  

• code

  func removeExpiredReminders() {
  
       let pastPredicate = eventStore.predicateForIncompleteRemindersWithDueDateStarting(nil, ending:NSDate(), calendars:[calendar])
  
      eventStore.fetchRemindersMatchingPredicate(pastPredicate) { foundReminders in
  
          let remindersToDelete = !foundReminders.isEmpty
          for reminder in foundReminders  as! [EKReminder] {
              self.eventStore.removeReminder(reminder, commit: false, error: nil)
          }
          if remindersToDelete {
              self.eventStore.commit(nil)
          }
      }
  }
  

in the loop you can check for further conditions