Check EKEvent out
EKEventStore *eventDB = [[EKEventStore alloc] init];
EKEvent *myEvent = [EKEvent eventWithEventStore:eventDB];
myEvent.title = @"New Event";
myEvent.startDate = [[NSDate alloc]init ];
myEvent.endDate = [[NSDate alloc]init ];
myEvent.allDay = YES;
[myEvent setCalendar:[eventDB defaultCalendarForNewEvents]];
NSError *err;
[eventDB saveEvent:myEvent span:EKSpanThisEvent error:&err];
UIAlertView *alert = [[UIAlertView alloc]
initWithTitle:@"Event Created"
message:@"Yay!?"
delegate:nil
cancelButtonTitle:@"Okay"
otherButtonTitles:nil];
[alert show];