objective-c - NSDateFormatter returns wrong date

Question

I have this piece of code:

 // Convert string to date object
        NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
        [dateFormat setDateFormat:@"MMMM d, YYYY"];
        NSDate *formatDate = [dateFormat dateFromString:self.date];
        NSLog(@"1-%@", self.date);
        NSLog(@"2-%@", formatDate);
        NSDateComponents *components = [[NSCalendar currentCalendar] components:NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit fromDate:formatDate];
        NSString *dateCal = [NSString stringWithFormat:@"%d/%d/%d", [components day], [components month], [components year]];
        NSLog(@"3-%@", dateCal);
        milage.date = dateCal;

The first NSLog returns:

1-March 23, 2012

The second:

2-2011-12-25 00:00:00 +0000

The third:

3-25/12/2011

Why does the date change when getting the date from the string and formatting it? I'm expecting the third NSLog (or dateCal) to equal 23/3/2012. I live in the UK so its not to do with the timezone..

Thanks,

Jack

I'm surprised that you see "March 23, 2012" when you NSLog self.date. On my machine, NSLog(@"%@", [NSDate date]); yields a date like "2012-03-23 14:47:48 +0000". — danh, Mar 23 '12 at 14:50
Here's a test, see whether this condition holds [self.date timeIntervalSinceReferenceDate] == [formatDate timeIntervalSinceReferenceDate]. (Ugly formatting, sorry, but since this isn't really an answer, I figured it should be a comment). — danh, Mar 23 '12 at 14:52
its a string, but why does my code work when I use the lower case 'yyyy' as opposed to 'YYYY'? — Jack Nutkins, Mar 23 '12 at 14:55
Oh. sorry for the dim-witted-ness. It looks like uppercase Y's mean week of the year. (http://unicode.org/reports/tr35/tr35-6.html#Date_Format_Patterns) — danh, Mar 23 '12 at 15:05

score 3 · Accepted Answer · answered Apr 16 '12 at 13:13

3

Needed to use lower case 'y' in the line:

[dateFormat setDateFormat:@"MMMM d, YYYY"];

answered Apr 16 '12 at 13:13

Jack Nutkins

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Why does the uppercase `YYYY` results in a wrong year? – Ricardo Sanchez-Saez Sep 03 '14 at 15:37
YYYY gives the week of the year, '1 Jan 2022' belongs to last week of 2021 so 'YYYY' return 2021 as year. – mhmtkrgz Apr 07 '22 at 07:54

score 2 · Answer 2 · answered Mar 23 '12 at 14:54

Have you used the setLocale method?

Also, from the technical Q&A:

If you're working with user-visible dates, you should avoid setting a date format string because it's very hard to predict how your format string will be expressed in all possible user configurations. Rather, you should try and limit yourself to setting date and time styles (via -[NSDateFormatter setDateStyle:] and -[NSDateFormatter setTimeStyle:]).

score 0 · Answer 3 · answered Mar 23 '12 at 14:57

0

Use [dateFormat setDateStyle:NSDateFormatterLongStyle];
Instead of [dateFormat setDateFormat:@"MMMM d, YYYY"];
Will give you reason as soon as I find it.

answered Mar 23 '12 at 14:57

Inder Kumar Rathore

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objective-c - NSDateFormatter returns wrong date

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