Core Data Predicate Date Comparison

Question

Im trying to fetch all the objects in an entity matching a user selectedDate (it\'s an NSDate). The Core Data code is fine but my predicate keeps returning 0 results, the da

Answer 1

While in human communication date often is equal with day, it is not the same with NSDate objects: A NSDate represents a single moment in time. Dates that are different just in seconds aren't equal. And actually they dont represent days, month, year at all, as this is different from calendar system to calendar system

you must define for yourself if dates in the same minute, hour, day … are equal. So basically you must teach the program to allow some fuzziness.

here for minute resolution

NSDate *startDate = ....;
NSTimeInterval length;

[[NSCalendar currentCalendar] rangeOfUnit:NSMinuteCalendarUnit 
                                startDate:&startDate
                                 interval:&length 
                                  forDate:startDate];

NSDate *endDate = [startDate dateByAddingTimeInterval:length];

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(eDate >= %@) AND (eDate < %@)", startDate, endDate];

For dates on the same day (aware of Timezones and Daylight Saving Times) you just would change this:

[[NSCalendar currentCalendar] rangeOfUnit:NSDayCalendarUnit 
                                startDate:&startDate
                                 interval:&length 
                                  forDate:startDate];