在iOS 12下,UNUserNotification不会发出本地通知

import UserNotifications

if #available(iOS 10.0, *) {
        let center = UNUserNotificationCenter.current()
        center.requestAuthorization(options: [.alert, .sound]) { _, _ in }
        let content = UNMutableNotificationContent()
        content.title = "Hello Staff"
        content.body = "Customer just ordered a milk with croissant"
        content.sound = UNNotificationSound.default()
        let date = Calendar.current.dateComponents([.year, .month, .day, .hour, .minute, .second], from: Date(timeIntervalSinceNow: 10))
        let trigger = UNCalendarNotificationTrigger(dateMatching: date, repeats: false)
        let request = UNNotificationRequest(identifier: "abcde", content: content, trigger: trigger)
        center.add(request)
}

AppDelegate . 但我看不到任何当地的通知。为什么?