How to sort an array of UNNotificationRequests by nextTriggerDate

Question

I have an array of UNNotificationRequest. I want to sort them by nextTriggerDate.

As far as I understand it, I would sort the array using array.sorted(by:predicate)

let sortedNotifications = notificationRequests.sorted(by: { $0.trigger.nextTriggerDate?.compare($1.trigger.nextTriggerDate!) == .orderedAscending })

However, the problem is .trigger doesn't have a nextTriggerDate property.

In order to obtain nextTriggerDate, I have to extract the trigger and cast it into UNCalendarNotificationTrigger. Which as far as I know, can't be done in a predicate.

Any thoughts?

Answer 1

You can create Tuple With UNNotificationRequest and nextTriggerDate (UNNotificationRequest,nextTriggerDate)

// get request with date Tuple -->  example : (value0,value1)

let requestWithDateTuple =  notificationRequests.map({ (req) -> (UNNotificationRequest,Date?)? in
                    guard let trigger = req.trigger as? UNCalendarNotificationTrigger else {
                        return nil
                    }
                    return (req,trigger.nextTriggerDate())
                }).compactMap({$0})

                // you will get Tuple (request,Date) ,sort them by date  
               let sortedTuple = requestWithDateTuple.sorted(by: { $0.1?.compare($1.1!) == .orderedAscending })

// sorted request only 
let requestSorted =  sortedTuple.map({$0.0})