ios - 检查日历中是否存在事件 - Swift

Question

我正在尝试检查事件是否已存在于日历中并显示它存在的警报。这是我下面的代码

已编辑:它不断添加重复事件。

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

问题是，即使事件存在，您添加事件的 do-catch block 也会一直被调用。您需要创建一个 bool 值来跟踪是否找到了相同的事件，并且仅在未找到时才执行 do-catch block 。

您可以使用 Array.contains(where:) 而不是使用 for 循环，它允许在发现此类事件时提前退出。

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")
    }
}