iOS 6 Programming Cookbook

16.7. Adding Alarms to Calendars

Problem

You want to add alarms to the events in a calendar.

Solution

Use the alarmWithRelativeOffset: class method of EKAlarm to create an instance of EKAlarm. Add the alarm to an event using the addAlarm: instance method of EKEvent, like so:

- (EKCalendar *)  getFirstModifiableLocalCalendar{
  
  EKCalendar *result = nil;
  
  EKEventStore *eventStore = [[EKEventStore alloc] init];
  
  for (EKCalendar *thisCalendar in eventStore.calendars){
    if (thisCalendar.type == EKCalendarTypeLocal &&
        [thisCalendar allowsContentModifications]){
      return thisCalendar;
    }
  }
  
  return result;
  
}

- (void) addAlarmToCalendar{
  
  EKCalendar *targetCalendar = [self getFirstModifiableLocalCalendar];
  
  if (targetCalendar == nil){
    NSLog(@"Could not find the target calendar.");
    return;
  }
  
  EKEventStore *eventStore = [[EKEventStore alloc] init];
  
  /* The event starts 60 seconds from now */
  NSDate *startDate = [NSDate dateWithTimeIntervalSinceNow:60.0f];
  
  /* And end the event 20 seconds after its start date */
  NSDate *endDate = [startDate dateByAddingTimeInterval:20.0f];
  
  EKEvent *eventWithAlarm = [EKEvent eventWithEventStore:eventStore];
  
  eventWithAlarm.calendar = targetCalendar;
  eventWithAlarm.startDate = startDate;
  eventWithAlarm.endDate = endDate;
  
  /* The alarm goes off two seconds before the event happens */
  EKAlarm *alarm = [EKAlarm alarmWithRelativeOffset:-2.0f];
  
  eventWithAlarm.title = @"Event with Alarm";
  [eventWithAlarm addAlarm:alarm];
  
  NSError *saveError = nil;
  
  if ([eventStore saveEvent:eventWithAlarm ...