What's wrong with how I'm using NSDateFormatter?

Question

   NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
   dateFormatter.locale = [[[NSLocale alloc] initWithLocaleIdentifier:@"en_US"] autorelease];
   [dateFormatter setDateFormat:@"EEE, d MMM yyyy HH:mm:ss zzz"];
   NSString *dateString = @"Tue, 08 Jun 2010 17:00:00 EDT";
   NSDate *eventDate = [dateFormatter dateFromString:dateString];

In this case the eventDate object is nil. Can somebody clue me in? This code used to work.

UPDATE: Can't talk about why this doesn't work due to NDA. Suffice it to say, when iOS 4 is out I will post the answer to my own question.

Answer 1

/*
    x           number
    xx          two digit number
    xxx         abbreviated name
    xxxx        full name

    a           AM/PM
    A           millisecond of day
    c           day of week (c,cc,ccc,cccc)
    d           day of month
    e           day of week (e,EEE,EEEE)
    F           week of month
    g           julian day (since 1/1/4713 BC)
    G           era designator (G=GGG,GGGG)
    h           hour (1-12, zero padded)
    H           hour (0-23, zero padded)
    L           month of year (L,LL,LLL,LLLL)
    m           minute of hour (0-59, zero padded)
    M           month of year (M,MM,MMM,MMMM)
    Q           quarter of year (Q,QQ,QQQ,QQQQ)
    s           seconds of minute (0-59, zero padded)
    S           fraction of second
    u           zero padded year
    v           general timezone (v=vvv,vvvv)
    w           week of year (0-53, zero padded)
    y           year (y,yy,yyyy)
    z           specific timezone (z=zzz,zzzz)
    Z           timezone offset +0000

    sql         y-M-d H:m:s
    rss         [E, ]d MMM y[y] H:m:s Z|z[zzz]
*/

This is my comment for date parsing. I use the following, where toDateUsingFormat uses an NSDateFormatter with the passed in string. I do not use a locale, because rss dates are not localized.

    if ( 0 == [string rangeOfString:@","].length ) {
        result = [string toDateUsingFormat:@"d MMM y H:m:s z"];
    } else {
        result = [string toDateUsingFormat:@"E, d MMM y H:m:s z"];
    }

Edit:

I use getObjectValue: instead of dateFromString.

NSDate *result = nil;
NSError *error = nil;
[dataFormatter getObjectValue:&result forString:dateString errorDescription:&error];

Answer 2

The full list of format specifiers is UTS#35 Date Format Patterns.

Does the 'c' character work in place of 'E'? The document has it as a very close alternative and it may produce the result you want.

(If you really want characters in the format string that are not in the table you can escape them, like hh 'o''clock' a, zzzz - produces format like "12 o'clock PM, Pacific Daylight Time".)

Answer 3

The problem that I found is that the string that I was parsing has some trailing characters "\n\t\t". The solution was to remove them:

[string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];