Он доступен в iPhone 4 SDK, поэтому в Monotouch. Взгляните на EKEventStore и EKEvent. Вот документы Apple .
Вот пример из страницы фрагментов Я держу:
public void CalendarEvents()
{
EKEventStore store = new EKEventStore();
EKCalendar calendar = store.DefaultCalendarForNewEvents;
// Query the event
if (calendar != null)
{
// Searches for every event in the next year
NSPredicate predicate = store.PredicateForEvents(NSDate.Now,DateTime.Now.AddDays(360),new EKCalendar[] {calendar});
store.EnumerateEvents(predicate, delegate(EKEvent currentEvent, ref bool stop)
{
// Perform your check for an event type
});
// Add a new event
EKEvent newEvent = EKEvent.FromStore(store);
newEvent.Title = "Lunch at McDonalds";
newEvent.Calendar = calendar;
newEvent.StartDate = DateTime.Now.Today;
newEvent.EndDate = DateTime.Now.Today.AddDays(1);
newEvent.Availability = EKEventAvailability.Free;
store.SaveEvent(newEvent, EKSpan.ThisEvent, new IntPtr());
}
}