Auto-renewable subscription receipt date format

Question

I'm struggling to figure out the formatting for the following date:

2011-05-24 19:02:32 Etc/GMT

This date is returned from Apple's receipt validation service and I need to turn it into a NSDate for some comparison operations. The real trouble is related to the timezone.

Here's some code I've already written:

        NSDictionary *receiptData = [info valueForKey:@"expires_date"];

        NSDateFormatter *f = [[NSDateFormatter alloc] init];

        [f setLocale:[NSLocale currentLocale]];
        [f setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
        [f setDateFormat:@"yyyy-MM-dd HH:mm:ss vvvv"];

        NSLog(@"%@", [f stringFromDate:[NSDate date]]);

        NSDate *subPurchaseDate = [f dateFromString:[receiptData valueForKey:@"original_purchase_date"]];

        [f release];

I've tried all combinations of 'v's and 'Z's that I can think of. Any insight?

Answer 1

By looking at the date format documentation I got the correct format, is works well for me:

        NSDateFormatter * formatter = [NSDateFormatter new];
        formatter.dateFormat = @"yyyy-MM-dd HH:mm:ss VV";

        NSDate * purchaseDate = [formatter dateFromString:latestTransaction[@"original_purchase_date"]];
        NSDate * expirationDate = [formatter dateFromString:latestTransaction[@"expires_date"]];

No need to set the time zone on the formatter since it's embedded in the string.
Manipulating the date string to parse it is not a good idea.

Source: http://www.unicode.org/reports/tr35/tr35-31/tr35-dates.html#Date_Format_Patterns