request local notification with specified scheduled time (date / interval)

LocalNotification.swift

import UserNotification

struct LocalNotification {
  static func isDuplicatedNotification(identifier: String, completion: @escaping (Bool) -> () = {_ in}) {
      UNUserNotificationCenter.current().getPendingNotificationRequests { notifications in
          let dumNotis = notifications.filter { $0.identifier == identifier }
          completion(!dumNotis.isEmpty)
      }
  }

  // FIXME : notification content currently unchangeable
  static func addNotification(identifier: String, scheduleTime: Date = Date(), interval: Double) {
      self.isDuplicatedNotification(identifier: identifier) { isDuplicated in
          if !isDuplicated {
              if let notiTime = Optional(scheduleTime.addingTimeInterval(interval)), notiTime.isFuture() {
                  let content = UNMutableNotificationContent()
                  content.title = "alarm"
                  content.body = "Tick! \(interval) seconds"

                  let trigger = UNTimeIntervalNotificationTrigger(timeInterval: notiTime.timeIntervalSinceNow, repeats: false)

                  let request = UNNotificationRequest(identifier: identifier, content: content, trigger: trigger)

                  UNUserNotificationCenter.current().add(request)
              } else {
                  print("notification time is past")
              }

          } else {
              print("duplicated noti, ignoring..")
          }
      }
  }

  static func addScheduleNotifications(identifier: String, scheduleTime: Date = Date(), intervals: [Double]) {
      for interval in intervals {
          self.addNotification(identifier: "\(identifier)_\(interval)", scheduleTime: scheduleTime, interval: interval)
      }
  }
}

// usage
LocalNotification.addScheduleNotifications(identifier: "identifier", scheduleItem: Date(), intervals: [5, 10])