Question

I’ve written a method as a category on NSDate which returns a string from a date. The format is {four year digits}{two month digits}{two day digits}. For some reason, the formatter returns the current year as the four year digits instead of returning the year of the date. Here’s my code:

- (NSString *) YYYYMMDD{
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];

    [formatter setTimeStyle:NSDateFormatterNoStyle];
    [formatter setDateStyle:NSDateFormatterFullStyle];
    [formatter setDateFormat:@"YYYYMMdd"];   // This line is doing something odd, not sure why yet.

    NSString *dateAsString = [formatter stringFromDate:self];

    NSLog(@"Date: %@ String: %@", [self description], dateAsString);

   return dateAsString;

}

Looking at the line that is logged, you’ll notice that the year is inflexible and sticks to the current year, even if the year which should be represented by the date object isn’t the current year.

Any idea why this is? Am I using an incorrect formatter?

Answer 1

As mentioned in a comment in the Data Formatting Guide:

A common mistake is to use
YYYY. yyyy specifies the calendar year whereas YYYY specifies the year
(of “Week of Year”), used in the ISO year-week calendar. In most
cases, yyyy and YYYY yield the same number, however they may be
different. Typically you should use the calendar year.

So try:

[formatter setDateFormat:@"yyyyMMdd"];