Question

I frequently use the NSDate compare method – but I want to consider two dates similar if they are equal in year, month, day. I have made a procesure called “cleanDate” to remove the hour part before I compare.

-(NSDate*)cleanDate:(NSDate*)date {
    NSCalendarUnit unitflags;
    NSDateComponents *component;  
    NSCalendar *calendar;
    calendar=[[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar]autorelease];
    unitflags=NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit;
    component=[calendar components:unitflags fromDate:date];
    return [calendar dateFromComponents:component]; //Dato uten klokke    
}

But my dates come out as:

2011-10-28 22:00:00
and some dates as:
2011-10-28 23:00:00

I want the hour part to be similar, e.g. 00:00.

Whats wrong? Does it have something to do with daylight saving time? Other? Thanks.

Answer 1

Seems like this is a Time Zone issue…
I thought NSLog would default to the local time zone – but it seems to default to GMT…

Date with GMT time zone is: Sat, 29 Oct 2011 22:00:00 GMT+00:00
Date with system time zone is: Sun, 30 Oct 2011 00:00:00 GMT+02:00
NSlog shows 2011-10-29 22:00:00 +0000

When using NSLog(@"NSlog shows %@",finalDate); it seems to print the GMT time... 
When using this code - I will get the local date in my time zone:

NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
[dateFormatter setDateFormat:@"EEE, d MMM yyyy HH:mm:ss z"];
[dateFormatter setTimeZone:[NSTimeZone systemTimeZone]];
NSString *dateString = [dateFormatter stringFromDate:myDate];
NSLog(@"Date with system time zone is: %@",dateString);

… so my original cleanDate actually seems to do what I want after all…