从闭包中的函数返回

Question

我需要在Swift的某一天获得一系列事件。因为EKEventStore.requestAccessToEntityType是异步运行的，所以我使用dispatch_group_notify等待EKEventStore.requestAccessToEntityType的完成处理程序完成，所以我可以用它做一些事情然后返回它。但我无法从闭包中的函数返回我传递给dispatch_group_notify，因为它尝试从闭包返回，而不是函数。这是我的代码

    class func eventsOn(date: NSDate) -> [Event] {
        var events = [Event]()

        var ekEvents = [EKEvent]()

        var dispatch_group = dispatch_group_create()

        dispatch_group_enter(dispatch_group)

        Event.eventStore.requestAccessToEntityType(EKEntityTypeEvent, completion: {
            gotAccess, error in
            let cal = NSCalendar.currentCalendar()
            var comps = cal.components(.CalendarUnitYear | .CalendarUnitMonth | .CalendarUnitDay, fromDate: date)

            let aFewHoursAgo = NSDateComponents()
            aFewHoursAgo.hour = -5

            var daStartDate = cal.dateFromComponents(comps)!
            daStartDate = cal.dateByAddingComponents(aFewHoursAgo, toDate: daStartDate, options: .allZeros)!

            var aDay = NSDateComponents()
            aDay.day = 1

            var daEndDate = cal.dateByAddingComponents(aDay, toDate: daStartDate, options: .allZeros)!
            daEndDate = daEndDate.dateByAddingTimeInterval(-1)!

            let p = Event.eventStore.predicateForEventsWithStartDate(daStartDate, endDate: daEndDate, calendars: [Event.eventStore.defaultCalendarForNewEvents])
            let tmp = Event.eventStore.eventsMatchingPredicate(p) as [EKEvent]?
            if let _ = tmp {
                ekEvents = tmp!
            }

            dispatch_group_leave(dispatch_group)
        })

        let queue = dispatch_get_global_queue(Int(QOS_CLASS_USER_INITIATED.value), 0)

        dispatch_group_notify(dispatch_group, queue) {
            println(ekEvents)

            let ekEventId = Expression<String>("ekEventId")
            let eventId = Expression<Int>("id")

            for ekEvent in ekEvents {
                let daEventId = Event.db["events"].filter(ekEventId == ekEvent.eventIdentifier).select(eventId).first![eventId]
                events.append(Event.eventWithId(daEventId)!)
            }

            return events
        }
    }

所以我将return events放在我传递给dispatch_group_notify的块中，它试图从闭包返回，但我想从函数返回。我怎么能这样做？