После выполнения следующего кода
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *expiryDateComponents = [calendar components:(NSCalendarUnitEra|NSCalendarUnitYear|NSCalendarUnitMonth|NSCalendarUnitDay) fromDate:aDate];
вы получаете следующее исключение без сбоев
*** -[__NSCFCalendar dateFromComponents:]: components cannot be nil
Future exception.
A few of these errors are going to be reported with this complaint, then further violations will simply be ignored.