RFC 3339 Date format - Decreasing date for PST timezone

Question

kalyanraju2001 OP

Created Feb ’17

Replies 1

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Participants 2

Hi All,

We have received a bug in our application saying that the values were shifted by one day back.

We have developed this application using the Objctive-C and please find the code snippet below.

-(NSString *)getDisplayDateFormat:(NSString *)dateString

{

NSLocale * enUSPOSIXLocale;

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

enUSPOSIXLocale = [NSLocale localeWithLocaleIdentifier:@"en_US_POSIX"];

[inputformatter setLocale:enUSPOSIXLocale];

inputformatter.timeZone = [NSTimeZone timeZoneForSecondsFromGMT:0];

[inputformatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ssZZZZZ"];

NSDate *date= [inputformatter dateFromString:dateString];

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

[OutPutformatter setDateStyle: NSDateFormatterShortStyle];

NSString *dispalyDateString = [OutPutformatter stringFromDate:date];

return dispalyDateString;

}

dateString = 2017-01-16T00:00:00-06:00

date = 2017-01-16 06:00:00 +0000

displayDateString = 1/15/17

I have given the input a 16th Feb but got the output 15th Feb. Need your inputs to resolve the issue.

Boost

Answer 1

DTS Engineer OP

Apple

Mar ’17

dateString = 2017-01-16T00:00:00-06:00

date = 2017-01-16 06:00:00 +0000

displayDateString = 1/15/17

These results make perfect sense to me:

```
dateString
```
is the start of (that is, midnight) 16 Jan, UTC-6
That translates to 6am UTC, which is what
```
date
```
shows
8 hours earlier than that is 10pm on 15 Jan, hence
```
displayDateString
```

Thinking about it in terms of the US vernacular, midnight in Central on day N translates to 10pm in Pacific on day N-1.

I think the problem here is one of specification. You’ve taken an absolute position in time and mapped it from one time zone to another and then are weirded out by the fact that the date has changed, but such changes are completely normal. If you want to display the same date everywhere, you have to change your approach, something that’s completely fine to do. If you can describe the approach you want to use, I can point you in the right direction API-wise. However, you’ll have to come up with the basic approach, because that’s something that has to make sense to you and your users.

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