dispatch_assert_queue_fail

最近开发遇到了APP莫名的闪退的问题，后来查阅stackview文献得出结论是系统线程导致的在此记录一下

事件经过
在日历中添加事件的回调中更新UI事件，未声明在主线程操作，导致莫名闪退

解决方案
使用DispatchQueue.main.async {}更新UI

结果
不再闪退

源码

let eventStore = EKEventStore.init()
eventStore.requestAccess(to: .event) { (granted, error) in

    if error != nil {
        DispatchQueue.main.async {
             ToastView.show(withTitle: "保存日历出错了")
            self.noticeBtn.isSelected = false
        }
        
    } else {
        if granted == false {
            DispatchQueue.main.async {
                ToastView.show(withTitle: "请开启日历权限")
                self.noticeBtn.isSelected = false
            }
        } else {
            DispatchQueue.main.async {
                // 创建日程
                let event = EKEvent.init(eventStore: eventStore)
                event.title = "日历内容"
                event.notes = "日历内容"
                event.startDate = Date(timeIntervalSince1970: TimeInterval(_startTime))
                event.endDate = Date(timeIntervalSince1970: TimeInterval(_startTime + 3600))
                event.isAllDay = false
                
                //日程提醒
                let alarm = EKAlarm.init(relativeOffset: -60.0)
                event.addAlarm(alarm)
                event.calendar = eventStore.defaultCalendarForNewEvents
                
                // 保存到系统
                var result: ()?
                do {
                    result = try eventStore.save(event, span: .thisEvent)
                } catch  {}
                
                if result != nil {
                    self.noticeBtn.setImage(UIImage(named: ""), for: .selected)
                    ToastView.show(withTitle: "日历提醒已开启")
                }
            }
        }
    }
}