Re: Daylight Savings Time
Re: Daylight Savings Time
- Subject: Re: Daylight Savings Time
- From: Peter Duniho <email@hidden>
- Date: Wed, 15 Apr 2009 12:47:39 -0700
On Apr 15, 2009, at 11:53 AM, Greg Robertson wrote:
I have put together some code from various sites such as this one:
http://blog.coriolis.ch/2009/02/20/relative-date-to-now/
Basically I would like to display records for a week duration but I am
unsure how to handle daylight savings time. Is there a way to see if
daylight savings time has or will occur?
The logic of my code is to display from Sunday to Saturday zeroing out
the current time to midnight but it does not appear to work well with
daylight savings which then sees one day overlapping another.
Anyone see or know of any code to deal with daylight savings time?
I don't have specific code examples. But, generally:
-- use something like NSTimeZone's "isDaylightSavingTime" or
"isDaylightSavingTimeForDate" to know whether a specific date/time is
in fact a daylight saving time
-- Convert your date/time information to UTC for actual
processing, using the DST information as appropriate; depending on
where the data comes from this may or may not result in ambiguity
during the Fall transition...you may have to ask the user whether the
local time is before or after the transition time, or just accept the
overlap in the results. But, if you can get the input to include the
exact time zone (e.g. "PST" versus "PDT") and/or the raw UTC offset,
this isn't an issue.
-- don't forget to use the correct term: "daylight saving time",
no plural. :)
Pete
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