Re: Getting NSTimeZone for a given NSDate
Re: Getting NSTimeZone for a given NSDate
- Subject: Re: Getting NSTimeZone for a given NSDate
- From: Jason Coco <email@hidden>
- Date: Mon, 15 Sep 2008 05:41:14 -0400
On Sep 15, 2008, at 05:35 , Jean-Daniel Dupas wrote:
Le 15 sept. 08 à 09:56, Jason Coco a écrit :
On Sep 15, 2008, at 03:49 , Markus Spoettl wrote:
Hi List,
I just know it must be there but I can't see it. How can I get to
the NSTimeZone for a given NSDate. When using -description: the
date got a time zone, so it's stored in there but how on earth can
I get to it? I only need the GMT offset (numerically, not as
string), in case there's a simpler way to obtain this.
All NSDate objects are stored as seconds since the reference date
(Jan 1 1970 00:00 GMT) and so are always GMT. The description is
using the default time zone to adjust the date. You can get the
default time zone with [NSTimeZone defaultTimeZone] and then you
can get the offset with -(NSTimeInterval)secondsFromGMT.
It's conceptualy right, but just for info, NSDate do not store the
value as a UNIX timestamp, but as a Core Foundation Absolute Time
which is a double that represents the number of seconds since the
reference date which is 00:00:00 1 January 2001
Oh yes yes, I actually knew it wasn't since the epoch, just very
tired :-) but yeah, seconds since 1 Jan 2001 not 1970! That'll teach
me to expand when I'm missing a lot of sleep... had I just said
"...since the reference date..." I would have been fine :)
J
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