Days between two dates (datediff)

NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSUInteger unitFlags = NSHourCalendarUnit | NSMinuteCalendarUnit | NSDayCalendarUnit;
NSDateComponents *components = [gregorianCalendar components:unitFlags
					fromDate:todaysDate
				        toDate:lastDate
					options:0];
[gregorianCalendar release];
 
NSString *days = [components day];