Like tkanzakic said,
NSDateComponents* components = [c components:(NSYearCalendarUnit|NSHourCalendarUnit|NSMinuteCalendarUnit|NSSecondCalendarUnit) fromDate:d1 toDate:d2 options:0] ;
NSLog(@"%ld years, %ld hours, %ld minutes, %ld seconds", components.year, components.hour, components.minute, components.second) ;