Cocoa-Touch: How do I see if two NSDates are in the same day?

Question

I need to know if two NSDate instances are both from the same day.

Is there an easier/better way to do it than getting the NSDateComponents and comparing day/month/year?

Answer 1

If you are targeting iOS 8 (and OS X 10.9) or later, then Joe's answer is a better solution using a new method in NSCalendar just for this purpose:

-[NSCalendar isDate:inSameDayAsDate:]

For iOS 7 or earlier: NSDateComponents is my preference. How about something like this:

- (BOOL)isSameDayWithDate1:(NSDate*)date1 date2:(NSDate*)date2 {
    NSCalendar* calendar = [NSCalendar currentCalendar];

    unsigned unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit |  NSDayCalendarUnit;
    NSDateComponents* comp1 = [calendar components:unitFlags fromDate:date1];
    NSDateComponents* comp2 = [calendar components:unitFlags fromDate:date2];

    return [comp1 day]   == [comp2 day] &&
           [comp1 month] == [comp2 month] &&
           [comp1 year]  == [comp2 year];
}

Answer 2

If you are working with iOS 8 you can use -isDate:inSameDayAsDate:.

From NSCalendar.h:

/*
    This API compares the Days of the given dates, reporting them equal if they are in the same Day.
*/
- (BOOL)isDate:(NSDate *)date1 inSameDayAsDate:(NSDate *)date2 NS_AVAILABLE(10_9, 8_0);

Note that for some reason this didn't make it to the official documentation on Apple's developer site. But it is definitely part of the public API.

Answer 3

(Note: Look at Joe's answer for a good way to do this on iOS 8+)

I just use a date formatter:

NSDateFormatter *dateComparisonFormatter = [[[NSDateFormatter alloc] init] autorelease];
[dateComparisonFormatter setDateFormat:@"yyyy-MM-dd"];

if( [[dateComparisonFormatter stringFromDate:firstDate] isEqualToString:[dateComparisonFormatter stringFromDate:secondDate]] ) {
    …
}

HTH.