Check if Event Exists in Calendar - Swift

I am trying to check if event already exists in calendar and show alert that it exists. This is my code below

Edited: It keeps adding Duplicate Events.

let event = EKEvent(eventStore: eventStore)
var savedEventId : String = ""
event.title = title
event.startDate = (self.dataEvent?.dates?.begin)!
event.endDate = (self.dataEvent?.dates?.end)!
event.calendar = eventStore.defaultCalendarForNewEvents
let predicate = eventStore.predicateForEventsWithStartDate(startDate, endDate: endDate, calendars: nil)
let existingEvents = eventStore.eventsMatchingPredicate(predicate)
for singleEvent in existingEvents {
    if singleEvent.title == self.dataEvent?.titleString && singleEvent.startDate == startDate && singleEvent.endDate == endDate {
        let alert = UIAlertController(title: "Event Already Exists", message: "Event Already Exists in Calendar", preferredStyle: UIAlertControllerStyle.Alert)
        alert.addAction(UIAlertAction(title: "Close", style: UIAlertActionStyle.Default, handler: nil))
        self.presentViewController(alert, animated: true, completion: nil)
    }
}
do {
    try eventStore.saveEvent(event, span: .ThisEvent)
    savedEventId = event.eventIdentifier
    print("Event Added")
    let alert = UIAlertController(title: "Event Successfully Added", message: "Event Added to Calendar", preferredStyle: UIAlertControllerStyle.Alert)
    alert.addAction(UIAlertAction(title: "Close", style: UIAlertActionStyle.Default, handler: nil))
    self.presentViewController(alert, animated: true, completion: nil)
} catch {
    print("Error occurred")
}