NSDate is 5 hours off

Question

I run the following code:

NSDate *now = [NSDate date];

NSLog(@"now: %@", now);

and get :

2011-09-16 16:14:16.434 iSavemore[1229:7907] now: 2011-09-16 21:14:16 +0000

As you can see i'm running this at 16:14:16 (4:14 pm) but NSDate is returning 21:16:16 (9:14 pm!). Is this an Xcode4 issue or NSDate issue?

Answer 1

NSDate defaults to the Universal timezone (aka GMT).

I'm guessing you're somewhere on the East Coast, 5 hours behind UTC.

Try adding this to your date formatter...

NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];

[dateFormatter setLocale:[NSLocale currentLocale]];

...and you should see your local time.

If you want to use a specified locale, rather than 'currentLocale', create a NSLocale for the relevant locale.

NSLocale *usLoc = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US"];

[dateFormatter setLocale:usLoc];

...actually that's US (so possibly not Central).

More specific timezone help can be found here...

http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSDateFormatter_Class/Reference/Reference.html

However, if you want to show expiry time, wouldn't you still want it in the user's currentLocale?

Answer 2

Try setting the time-zone of your NSDate to one that is fitting your need, for example [NSTimeZone localTimeZone]

Answer 3

Just a wild guess here, but maybe it has something to do with time zones?

Answer 4

If you look at the output you'll see that the log includes the timezone:

2011-09-16 16:14:16.434 iSavemore[1229:7907] now: 2011-09-16 21:14:16 +0000
                                                                      ^^^^^^

The time stamp of your log is local time. I assume you're in a timezone that is 5 hours ahead of UTC.

A NSDate refers to a particular point in time. It's up to you to display this however you want; usually with an NSDateFormatter.

This is the reason why you'll see plenty of recommendations against storing a time, or a date as anything other than an NSDate. If you try and store it as a string you'll run into a lot of trouble later on when trying to handle the display in different timezones.