The method has been renamed to -dateByAddingTimeInterval:.
localNotif.fireDate = [now dateByAddingTimeInterval:timeInterval];
In Swift 2.2:
localNotif.fireDate = now.dateByAddingTimeInterval(timeInterval)
In Swift 3:
localNotif.fireDate = now.addingTimeInterval(timeInterval)
// or simply
localNotif.fireDate = now + timeInterval