Avoid iOS EventKit startDate and endDate overlapping with existing events

I can successfully add some events to the Calendar, using this simple code snippet:

 var eventStore : EKEventStore = EKEventStore()
        eventStore.requestAccessToEntityType(EKEntityTypeEvent, completion: {
            granted, error in
            if (granted) && (error == nil) {
                println("Access granted to calendar \(granted)")
                println("No error or error is simply \(error)")
                
                var event:EKEvent = EKEvent(eventStore: eventStore)
                event.title = fullTitle
                event.startDate = startDate
                event.endDate = endDate
                event.notes = "This is a note"
                event.calendar = eventStore.defaultCalendarForNewEvents
                eventStore.saveEvent(event, span: EKSpanThisEvent, error: nil)
                println("Saved Event")
            }

I can handle errors and authorisation issues, but I want to be sure that there's no overlap, not even by a minute when I add a new Calendar event with an existing one.

By default it just "overload", I could set many events at the very same time but I don't want this behaviour... So, what I mean is that startDate and endDate should be set on an empty slot, if something is already set in between I want to be notified in advance.

I read the EventKit documentation but is kind of cumbersome to me, also the examples I found vary in galore from the code I got, which is working fine.

You can search if the event exists before you save it. If the event exists just doesn't add it.

To find if event exists you can use something like:

NSString *predicateString= [NSString stringWithFormat:@"title == '%@' AND location == '%@' AND notes == '%@'", event.title, event.location, event.notes ];
    
    NSPredicate *matches = [NSPredicate predicateWithFormat:predicateString];
    
    NSArray *datedEvents = [self.eventStore eventsMatchingPredicate:[eventStore predicateForEventsWithStartDate:event.startDate endDate:event.endDate calendars:nil]]; //search in all calendars
    
    NSArray *matchingEvents = [datedEvents filteredArrayUsingPredicate:matches];