Check if Event Exists in Calendar - Swift

Question

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")
}

Answer 1

The problem is that your do-catch block in which you add the event gets called all the time even if the event exists. You need to create a boolean to track whether the same event was found or not and only execute the do-catch block if it wasn't found.

Instead of using a for loop, you can use Array.contains(where:), which allows for an early exit if such an event was found.

var eventAlreadyExists = false
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)

let eventAlreadyExists = existingEvents.contains(where: {event in self.dataEvent?.titleString == event.title && event.startDate == startDate && event.endDate = endDate})

// Matching event found, don't add it again, just display alert
if eventAlreadyExists {
    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)
} else {
    // Event doesn't exist yet, add it to calendar
    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")
    }
}

Answer 2

Note: If your endDate and startDate are equal - then use in predicate range of time, eg endDate + 1, startDate +1 in eventStore.predicateForEventsWithStartDate. Overwise your existingEvents will always empty