swift local notification

localnotif.swift

  let center = UNUserNotificationCenter.current()
  center.delegate = self
  center.requestAuthorization(options: [.alert, .badge, .sound]) { (granted, error) in
      if granted {
          print("Permission granted")

          let content = UNMutableNotificationContent()
          content.title = "My title"
          content.body = "Lots of text"
          content.sound = UNNotificationSound.default
          content.categoryIdentifier = "yourIdentifier"
          content.userInfo = ["example": "information"] // You can retrieve this when displaying notification

          // Setup trigger time
          var calendar = Calendar.current
          calendar.timeZone = TimeZone.current
          let testDate = Date().addingTimeInterval(20) // 20 seconds later from now. 
          let dateComponents = Calendar.current.dateComponents([.year, .month, .day, .hour, .minute, .second], from: testDate)
          let trigger = UNCalendarNotificationTrigger(dateMatching: dateComponents, repeats: false)
          // Create request
          let uniqueID = UUID().uuidString // Keep a record of this if necessary
          let request = UNNotificationRequest(identifier: uniqueID, content: content, trigger: trigger)
          DispatchQueue.main.async {
              center.add(request) // Add the notification request
          }
      } else {
          print("Permission denied\n")
      }
  }