Sort on (before or after today) in NSSortDescriptor

Question

I have a NSFetchedResultsController that feeds a UITableViewController with Appointment entities that have, among others, a property dateTime.

My goal is to have a list of appointments sorted like this:

1. Today
2. Tomorrow
3. Day after tomorrow
4. Yesterday
5. Day before yesterday

In other words: First sort on whether it's before or after today, then on dateTime. So first sort on (dateTime > %TODAY%), then on dateTime itself (future ascending, past descending).

Is there any way to do this? My problem is that I can't use %TODAY% in a sort descriptor, but maybe there's another way to achieve the same visual result.

UPDATE: Be aware the accepted answer is not possible with a NSFetchedResultsController. I chose another solution, ordering the Appointments before showing the view., saving that to the database, and let the NSFetchedResultsController pick up the changes.

UPDATE 2: Accepted answer did to do exactly what I wanted. My implementation:

let futureAppointments = appointments.filter({ $0.dateTime != nil && $0.dateTime?.compare(Date()) == .orderedDescending })
    .sorted(by: { $0.dateTime?.compare($1.dateTime! as Date) == .orderedAscending })

let pastAppointments = appointments.filter({ $0.dateTime != nil && $0.dateTime?.compare(Date()) == .orderedAscending })
    .sorted(by: {  $0.dateTime?.compare($1.dateTime! as Date) == .orderedDescending })

let sorted = futureAppointments + pastAppointments

for (index, appointment) in sorted.enumerated() {
    appointment.order = NSNumber(integerLiteral: index)
}

Answer 1

It's only idea. May be you can create sortdescriptor like this:

NSSortDescriptor(key: "test", ascending: true) { (v1, v2) -> ComparisonResult in
      guard let d1 = v1 as? Date else
      {
          return .orderedAscending
      }
      guard let d2 = v2 as? Date else
      {
        return .orderedAscending
      }
      if abs(d1.timeIntervalSinceNow) < abs(d2.timeIntervalSinceNow) { return .orderedAscending }
      if abs(d1.timeIntervalSinceNow) > abs(d2.timeIntervalSinceNow) { return .orderedDescending }
      return .orderedSame
}

I think it will be work.