NSFetchedResultsController update every minute with observable NSDate of today?

Question

I have a list of results showing on the UI for the current NSDate. Every minute, I need this list and another field to update (although a change may not occur every minute).

I am using an NSFetchedResultsController with an NSPredicate and a static variable holding the NSDate at the time.

Now I could simply reset the NSFetchedResultsController every minute, but with an observable coredata set that seems a little crude.

Is there a way to make that NSDate variable observable, such that coredata will reevaluate the NSPredicate when it's updated?

var today: NSDate = NSDate()
predicate: NSPredicate(format: "startTime > %@ AND endTime < %@" /* AND classCodeNumber != nil" */, today.startOfDay(), today.endOfDay())!...

With passing time, this predicate should change the set of data shown.