Comparing two NSDates and ignoring the time component

Question

What is the most efficient/recommended way of comparing two NSDates? I would like to be able to see if both dates are on the same day, irrespective of the time and have started writing some code that uses the timeIntervalSinceDate: method within the NSDate class and gets the integer of this value divided by the number of seconds in a day. This seems long winded and I feel like I am missing something obvious.

The code I am trying to fix is:

if (!([key compare:todaysDate] == NSOrderedDescending))
{
    todaysDateSection = [eventSectionsArray count] - 1;
}

where key and todaysDate are NSDate objects and todaysDate is creating using:

NSDate *todaysDate = [[NSDate alloc] init];

Regards

Dave

Answer 1

You set the time in the date to 00:00:00 before doing the comparison:

unsigned int flags = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay;
NSCalendar* calendar = [NSCalendar currentCalendar];

NSDateComponents* components = [calendar components:flags fromDate:date];

NSDate* dateOnly = [calendar dateFromComponents:components];

// ... necessary cleanup

Then you can compare the date values. See the overview in reference documentation.