iOS: Compare two NSDate-s without time portion

Question

I want to compare two dates: date1 and date2

2011-06-06 12:59:48.994 Project[419:707] firstDate:2011-06-06 10:59:21 +0000 2011-06-06 12:59:49.004 Project[419:707] selectedData:2011-06-06 10:59:17 +0000 

but these dates have different time and when I use NSOrderedSame it don't work fine, how can I solve?

my code:

NSDate *firstDate = [[appDelegate.project objectAtIndex:i]objectAtIndex:3]; NSDate *secondDate = [[appDelegate.project objectAtIndex:i]objectAtIndex:4];  NSCalendar *calendar = [NSCalendar currentCalendar]; NSInteger comps = (NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit);  NSDateComponents *date1Components = [calendar components:comps                                                              fromDate:firstDate]; NSDateComponents *date2Components = [calendar components:comps                                                              fromDate:secondDate]; NSDateComponents *date3Components = [calendar components:comps fromDate:appDelegate.selectedDate];  NSLog(@"firstDate:%@", [date1Components date]); NSLog(@"secondDate:%@", [date2Components date]); NSLog(@"selectedData:%@", [date3Components date]);  NSComparisonResult compareStart = [[date1Components date] compare: [date3Components date]];  NSComparisonResult compareEnd = [[date2Components date] compare: [date3Components date]];   if ((compareStart == NSOrderedAscending || compareStart == NSOrderedSame)      && (compareEnd == NSOrderedDescending || compareEnd == NSOrderedSame))  {     NSLog(@"inside"); 

Then I want to compare my dates and entry inside the "if" when date1 <= selectedDate <= date2; now I understand because I have a warning: I should add this "[date1Components date]" and it work; the problem is that I have in the NSLog null values, why??

Answer 1

NSCalendar *calendar = [NSCalendar currentCalendar]; NSInteger comps = (NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear);  NSDateComponents *date1Components = [calendar components:comps                                                  fromDate: date1]; NSDateComponents *date2Components = [calendar components:comps                                                  fromDate: date2];  date1 = [calendar dateFromComponents:date1Components]; date2 = [calendar dateFromComponents:date2Components];  NSComparisonResult result = [date1 compare:date2]; if (result == NSOrderedAscending) { } else if (result == NSOrderedDescending) { }  else {     //the same } 

---

There is another handy method to create for a given date the date that represents the start of a given unit: [aCalendar rangeOfUnit:startDate:interval:forDate:]
To illustrate how this method works, see this code, that easily creates the date for the beginning of the day, week, month and year for a given date (here: now).

NSDate *now = [NSDate date]; NSDate *startOfToday = nil; NSDate *startOfThisWeek = nil; NSDate *startOfThisMonth = nil; NSDate *startOfThisYear = nil; [[NSCalendar currentCalendar] rangeOfUnit:NSDayCalendarUnit startDate:&startOfToday interval:NULL forDate:now]; [[NSCalendar currentCalendar] rangeOfUnit:NSWeekCalendarUnit startDate:&startOfThisWeek interval:NULL forDate:now]; [[NSCalendar currentCalendar] rangeOfUnit:NSMonthCalendarUnit startDate:&startOfThisMonth interval:NULL forDate:now]; [[NSCalendar currentCalendar] rangeOfUnit:NSYearCalendarUnit startDate:&startOfThisYear interval:NULL forDate:now];  NSDateFormatter *formatter = [[NSDateFormatter alloc] init]; [formatter setDateStyle:NSDateFormatterFullStyle]; [formatter setTimeStyle:NSDateFormatterFullStyle];  NSLog(@"%@", [formatter stringFromDate:now]); NSLog(@"%@", [formatter stringFromDate:startOfToday]); NSLog(@"%@", [formatter stringFromDate:startOfThisWeek]); NSLog(@"%@", [formatter stringFromDate:startOfThisMonth]); NSLog(@"%@", [formatter stringFromDate:startOfThisYear]); 

result:

Thursday, July 12, 2012, 4:36:07 PM Central European Summer Time  Thursday, July 12, 2012, 12:00:00 AM Central European Summer Time  Sunday, July 8, 2012, 12:00:00 AM Central European Summer Time  Sunday, July 1, 2012, 12:00:00 AM Central European Summer Time  Sunday, January 1, 2012, 12:00:00 AM Central European Standard Time 

this allows us to shorten the first code to:

[[NSCalendar currentCalendar] rangeOfUnit:NSDayCalendarUnit startDate:&date1 interval:NULL forDate:date1]; [[NSCalendar currentCalendar] rangeOfUnit:NSDayCalendarUnit startDate:&date2 interval:NULL forDate:date2];  NSComparisonResult result = [date1 compare:date2]; if (result == NSOrderedAscending) { } else if (result == NSOrderedDescending) { }  else {     //the same } 

Note, that in this code, date1 and date2 will be overwritten. Alternatively you can pass in a reference to another NSDate pointer for startDate as shown in the code above, where now stays untouched.