How to set specific alarm in EKEvent in ios calendar?

Question

In EKEvent, once i haven't set any alarm to event then i check in calendar app and it show me alert before 5 min. why ? i did not understand it.

my requirement

• i want to set two alert, 1 alert on before given specific time like "5 minute, 15 minute, 30 minute, 1 hour". 2 second alert want set on event time.

• On the base of searching how to add alarm in event i did something for add event but however it doesn't work. lot of try but no effect in calendar.

• see below code i have tried both way as per my requirement i use switch case and even try to add single alarm. Both not work.

what should i have to do ?

give any suggestions, solution, idea

Thanks

       let event:EKEvent = EKEvent(eventStore: appleEventStore)

        event.title = tempDescription
        event.startDate = startDate as Date
        event.endDate = endDate as Date
        event.isAllDay = false
        event.notes = "This is a note"
        event.calendar = cal
        do {
            try appleEventStore.save(event, span: .thisEvent)
            print("events added with dates:")

            let alarm = EKAlarm(relativeOffset: 600)
            event.addAlarm(alarm)

            switch tempalertid {

            case "1":
                let aInterval: TimeInterval = -5 * 60
                let alaram = EKAlarm(relativeOffset: aInterval)
                event.addAlarm(alaram)
            case "2":
                let aInterval: TimeInterval = -15 * 60
                let alaram = EKAlarm(relativeOffset: aInterval)
                event.addAlarm(alaram)
            case "3":
                let aInterval: TimeInterval = -30 * 60
                let alaram = EKAlarm(relativeOffset: aInterval)
                event.addAlarm(alaram)
            case "4":
                let aInterval: TimeInterval = -1 * 60 * 60
                let alaram = EKAlarm(relativeOffset: aInterval)
                event.addAlarm(alaram)

            default:
                break
            }
            if event.hasAlarms {
                print("yes")

            }
            else {
                print("no")
            }

        } catch let e as NSError {
            print(e.description)
            return
        }
        print("Saved Event")

Answer 1

    let event:EKEvent = EKEvent(eventStore: appleEventStore)
    event.title = tempDescription
    event.startDate = startDate as Date
    event.endDate = endDate as Date
    event.isAllDay = false
    event.notes = "This is a note"
    event.calendar = cal


    switch tempalertid {
        case "1":
            let aInterval: TimeInterval = -5 * 60
            let alaram = EKAlarm(relativeOffset: aInterval)
             event.alarms = [alaram]
        case "2":
            let aInterval: TimeInterval = -15 * 60
            let alaram = EKAlarm(relativeOffset: aInterval)
             event.alarms = [alaram]
        case "3":
            let aInterval: TimeInterval = -30 * 60
            let alaram = EKAlarm(relativeOffset: aInterval)
             event.alarms = [alaram]
        case "4":
            let aInterval: TimeInterval = -1 * 60 * 60
            let alaram = EKAlarm(relativeOffset: aInterval)
            event.alarms = [alaram]

        default:
            break
        }

    do {
        try appleEventStore.save(event, span: .thisEvent)
        print("events added with dates:")

    } catch let e as NSError {
        print(e.description)
        return
    }
    print("Saved Event")