Schedule Notification to trigger at specific time - Swift

Question

In my app, I have a uidatepickerview that lets the user pick a time. Currently in my code I have that time selected passed as dateA. I then looped through all of the days that are selected in a separate uitableview, and checked to see if they were equal to today's day(such as Tuesday). If the days were the same, then I a notification would send at the selected time that was passed as dateA. However, when I try to send the notification, it is not sent.

Here is a snippet of my code showing what I have tried:

    var dateA: Date? = nil//where selected time is kept

    var weekdaysChecked = [String]()//where selected weekdays are kept

    var alarms = [Alarm]() {
        didSet {
            tableView.reloadData()
        }
    }


    override func viewDidLoad() {
        UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .sound], completionHandler: { (didAllow, error) in
        })

    }


    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "alarmCell", for: indexPath) as! DisplayAlarmCell

        let row = indexPath.row
        let alarm = alarms[row]
        let date = Date()
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat  = "EEEE"//"EE" to get short style
        let dayInWeek = dateFormatter.string(from: date)


        if(alarms.count == 40) {
            self.navigationItem.rightBarButtonItem?.isEnabled = false
            tableView.reloadData()
        }

        cell.alarmTitle.text = alarm.alarmLabel
        cell.clockTitle.text = alarm.time

        for weekdays in weekdaysChecked {
            if(dayInWeek == weekdays){
                let content = UNMutableNotificationContent()
                content.title = alarm.alarmLabel!
                content.subtitle = alarm.time!
                content.sound = UNNotificationSound(named: "Spaceship_Alarm.mp3")

                let trigger = Calendar.current.dateComponents([.hour,.minute], from: dateA!)
                let triggerNotif = UNCalendarNotificationTrigger(dateMatching: trigger, repeats: false)

                let triggerRequest = UNNotificationRequest(identifier: "AlarmNotif", content: content, trigger: triggerNotif)

                UNUserNotificationCenter.current().add(triggerRequest, withCompletionHandler: nil)

                print("This is the correct day.")
            }
        }

Answer 1

Assuming you're seeing your "This is the correct day" message, a candidate problem is the use of a fixed identifier for your UNNotificationRequest. As the docs say, "if identifier is not unique, notifications are not delivered".

Also, I'd suggest adding an error message if the requestAuthorization call failed. Right now, if permission failed for any reason, you won't know and no notifications would be delivered.

---

Unrelated, cellForRowAt is not the right place to be creating notifications. If a user doesn't happen to scroll the particular cell into view, no notification will be created. And if the user scroll a cell out of view and then back into view, you'll attempt to create the same notification request again. Bottom line, whether a cell happens to appear or not (and whether it reappears again later) is unrelated to whether the notifications should be created or not.

The creation of notifications belongs where you update the model (or in response to some user action, like checking a checkbox or the like).