iOS 6 Programming Cookbook

16.8. Handling Event Changed Notifications

Problem

You want to get notified in your application when the user changes the contents of the Calendar database.

Solution

Register for the EKEventStoreChangedNotification notification:

- (EKCalendar *) 
    calDAVCalendarWithTitleContaining:(NSString *)paramDescription
                         inEventStore:(EKEventStore *)paramEventStore{
  
  EKCalendar *result = nil;
  
  for (EKCalendar *thisCalendar in paramEventStore.calendars){
    if (thisCalendar.type == EKCalendarTypeCalDAV){
      if ([thisCalendar.title 
           rangeOfString:paramDescription].location != NSNotFound){
        return thisCalendar;
      }
    }
  }
  
  return result;
  
}

- (void) eventsChanged:(NSNotification *)paramNotification{
  
  NSMutableArray *invalidatedEvents = [[NSMutableArray alloc] init];
  
  NSLog(@"Refreshing array of events...");
  
  for (EKEvent *event in self.eventsForOneYear){
    if ([event refresh] == NO){
      [invalidatedEvents addObject:event];
    }
  }
  
  if ([invalidatedEvents count] > 0){
    [self.eventsForOneYear removeObjectsInArray:invalidatedEvents];
  }
  
}

- (BOOL)            application:(UIApplication *)application
  didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{
  
  self.eventStore = [[EKEventStore alloc] init];
  
  EKCalendar *calendar = 
  [self calDAVCalendarWithTitleContaining:@"[e-mail]"
                             inEventStore:self.eventStore];
  
  NSTimeInterval NSOneYear = 1 * 365 * 24 * 60 * 60;
  
  NSDate *startDate = [NSDate date];
  NSDate *endDate = [startDate dateByAddingTimeInterval:NSOneYear];
  
  NSArray *calendars = [[NSArray alloc] initWithObjects:calendar, nil];
  
  NSPredicate ...