How to read a local notification's trigger DateComponents in Swift?

My application is meant to deliver a daily notification with some content specific for that day. I know that iOS can store up to 64 future scheduled notifications, so I'm looking for a way to make sure that tomorrow's notification is always ready to fire, even if the user hasn't opened the app in more than a day.

To that end, in my main ViewModel I have a function that does that, but first it cancels all pending notifications to ensure there are no duplicates. However, this is obviously not the best approach.

So, here's my question: I use the class and function below to list all pending notifications. I can access the trigger, but how do I get the actual date in it, so that I can perform some logical check (e.g. only delete those requests that are 2+ days in the future)?

class LocalNotificationManager {
    
    static let shared = LocalNotificationManager()
    var notifications = [Notification]()
    let NC = UNUserNotificationCenter.current()
    
    func listScheduledNotifications() {
        NC.getPendingNotificationRequests { notifications in
            
            for notification in notifications {
                print("Notification [\(notification.identifier)], \(String(describing: notification.trigger))")
                
            }
            print("Pending notifications: [\(notifications.count)]")
        }
    }
}

Here's a sample output of this function:

Notification [2023-07-28_AB5DD5E7-45F6-47E7-8A98-7670C3C8214F],
Optional(<UNCalendarNotificationTrigger: 0x6000023f8040; 
dateComponents: <NSDateComponents: 0x600002198dd0> {
    Calendar Year: 2023
    Month: 7
    Day: 28
    Hour: 10
    Minute: 15, repeats: NO>)

You should cast notification.trigger to UNCalendarNotificationTrigger. This may fail, as not all triggers are based on date components. You should decide what you want to do with the ones not based on date components.

if let trigger = notification.trigger as? UNCalendarNotificationTrigger {
    // check if the next time this notification triggers is within two days
} else {
    // not based on date components...
}

As for how you check if check if the next time this notification triggers is within two days, you can use nextDate(after:matching:matchingPolicy:repeatedTimePolicy:direction:) to get a Date, and then check if the Date is within 2 days.

let calendar = Calendar.current
if let nextTriggerInstant = calendar.nextDate(after: Date(), matching: trigger, matchingPolicy: .strict) {
    if nextTriggerInstant.timeIntervalSinceNow > 60 * 60 * 48 { // 48 hours
        // delete the notification
    }
}

Note that the above checks if nextTriggerInstant is within the next 48 hours. If you want a date-based calculation (only looking at the year-month-day components), use dateComponents(_:from:to:).

let dateComponentsNow = calendar.dateComponents([.year, .month, .day], from: Date())
let dateComponentsAtTrigger = calendar.dateComponents([.year, .month, .day], from: nextTriggerInstant)
let days = calendar.dateComponents([.day], from: dateComponentsNow, to: trigger)
if days > 2 {
    // delete...
}