How do I create the current date (or any date) as an NSDate without hours, minutes and seconds?

Question

I need to create an NSDate of the current date (or on any NSDate) without the hours, minutes and seconds and keep it as an NSDate, in as few lines

Answer 1

First, you have to understand that even if you strip hours, minutes and seconds from an NSDate, it will still represent a single moment in time. You will never get an NSDate to represent an entire day like 2011-01-28; it will always be 2011-01-28 00:00:00 +00:00. That implies that you have to take time zones into account, as well.

Here is a method (to be implemented as an NSDate category) that returns an NSDate at midnight UTC on the same day as self:

- (NSDate *)midnightUTC {
    NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    [calendar setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];

    NSDateComponents *dateComponents = [calendar components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit
                                                   fromDate:self];
    [dateComponents setHour:0];
    [dateComponents setMinute:0];
    [dateComponents setSecond:0];

    NSDate *midnightUTC = [calendar dateFromComponents:dateComponents];
    [calendar release];

    return midnightUTC;
}

Answer 2

NSDate *oldDate = [NSDate date];
NSCalendarUnit requiredDateComponents = NSYearCalendarUnit| NSMonthCalendarUnit | NSDayCalendarUnit;    
NSDateComponents *components = [[NSCalendar currentCalendar] components:requiredDateComponents fromDate:oldDate]; 
NSDate *newDate = [[NSCalendar currentCalendar] dateFromComponents:components];