ふたつの日時の差を求めたい(年月日)

// ふたつの日時の差を求める(年月日のみ)
NSCalendar *calendar = [NSCalendar currentCalendar];

NSDateComponents *comps1 = [[NSDateComponents alloc] init];
[comps1 setYear:2009];
[comps1 setMonth:3];
[comps1 setDay:10];
NSDate *date1 = [calendar dateFromComponents:comps1];

NSDateComponents *comps2 = [[NSDateComponents alloc] init];
[comps2 setYear:2010];
[comps2 setMonth:5];
[comps2 setDay:20];
NSDate *date2 = [calendar dateFromComponents:comps2];

NSDateComponents *diff = [calendar components:(NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit) fromDate:date1 toDate:date2 options:0];

NSLog(@"Year: %d Month: %d Day: %d", [diff year], [diff month], [diff day]); // => Year: 1 Month: 2 Day: 10