Unique Identifier for scheduling notifications, Swift 3 iOS 10

Question

I am scheduling notifications with Unique Identifiers so I don't have to make a new String for each notification. This all works well for scheduling but the problem lies in trying to cancel them.

This is my code for scheduling notifications...

let notifIdentifier = TaskManager.notification2.userInfo.description as String!
let trigger = UNCalendarNotificationTrigger(dateMatching: components , repeats: true)
let request = UNNotificationRequest(identifier: notifIdentifier! , content: TaskManager.notification2, trigger: trigger)
UNUserNotificationCenter.current().add(request, withCompletionHandler: nil)

This is the code for cancelling notifications ...

// Deletion of Cells ...

func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
    
    let managedObject: NSManagedObject = frc.object(at: indexPath) as! NSManagedObject
    context.delete(managedObject)
    if tableView == TaskTableViews {
    let itemController = TaskManager()
    let nItem: List = frc.object(at: indexPath) as! List
    itemController.nItem = nItem
    UNUserNotificationCenter.current().removePendingNotificationRequests(withIdentifiers: [itemController.notifIdentifier!] )

When I try to cancel them, they are very hit and miss. I have tested the code by changing the identifier to a regular String and everything works as it should so its definitely the unique identifier.

Any thoughts/ suggestions on creating a unique ID for every new task/notification?

Answer 1

Scheduling notifications

@IBAction func scheduleNotification(_ sender: AnyObject) {

    let uuid = UUID().uuidString


    let content = UNMutableNotificationContent()
    content.title = NSString.localizedUserNotificationString(forKey: "Example", arguments: nil)
    content.sound = UNNotificationSound.default()
    //...

    var dateComponents = Calendar.current.dateComponents([.year, .month, .day, .hour, .minute], from: self.datePicker.date)
    dateComponents.second = 0

    let trigger = UNCalendarNotificationTrigger(dateMatching: dateComponents, repeats: false)

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

    UNUserNotificationCenter.current().add(request) { (error) in

        if let errorPerforms = error {
         print(errorPerforms.localizedDescription)
        } else {
         print("Success")
        }
    }


    let managedObject = ManagedObject(context: self.managedObjectContext!)
    managedObject.setValue(uuid, forKey: "uuid")
    //...

    do {
     try self.managedObjectContext.save()
        self.dimiss()
    } catch {}
}

Delete notifications from the indexPath.

 // Override to support editing the table view.
override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {

    switch editingStyle {
    case .delete:

        let managedObject = self.fetchedResultsController.object(at: indexPath)
        self.managedObjectContext.delete(managedObject)

        let center = UNUserNotificationCenter.current()
        center.removeDeliveredNotifications(withIdentifiers: [managedObject.uuid!])
        center.removePendingNotificationRequests(withIdentifiers: [managedObject.uuid!])

        do {
         try self.managedObjectContext.save()
            self.tableView.reloadData()
        } catch {}

    default:
        break
    }

}

This works well! When you're using the NSFetchedResultsControllerDelegate protocol methods. Hope it helps