How to send discreet notifications

notifications.swift

// The author disclaims copyright to this source code.  In place of
// a legal notice, here is a blessing:
// 
//    May you do good and not evil.
//    May you find forgiveness for yourself and forgive others.
//    May you share freely, never taking more than you give.

class YourViewController : UIViewController {
  // add this method.
  func sendDiscreetNotification(message: String) {
    if (! UIAccessibility.isGuidedAccessEnabled) { return }
    // Clear existing notifications from the stack.
    let center = UNUserNotificationCenter.current()
    center.removeAllDeliveredNotifications()
    center.removePendingNotificationRequests(withIdentifiers: ["unique_id"])

    // Create and show a new notification on an accessory.
    let content = UNMutableNotificationContent()
    content.body = message
    content.subtitle = ""
    content.title = "a title"

    let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 0.001, repeats: false)
    let request = UNNotificationRequest(identifier: "unique_id", content: content, trigger: trigger)
    UNUserNotificationCenter.current().delegate = self
    UNUserNotificationCenter.current().add(request, withCompletionHandler: nil)
  }
}

extension YourViewController : UNUserNotificationCenterDelegate {
    func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
                        completionHandler([.alert,.sound])
    }
}