Re: NSCalendar bug with adding to pre-1919 dates?
Re: NSCalendar bug with adding to pre-1919 dates?
- Subject: Re: NSCalendar bug with adding to pre-1919 dates?
- From: Greg Herlihy <email@hidden>
- Date: Wed, 01 Mar 2006 00:51:18 -0800
- Thread-topic: NSCalendar bug with adding to pre-1919 dates?
Since the time calculations are performed for a date and time in a specific
time zone (apparently U.S. Eastern) it would make sense that the time
reported would reflect any Daylight Saving Time adjustment needed to arrive
at the correct, local time. (A little bit of trivia: the "Saving" in
"Daylight Saving Time" does not end in an "s").
If the calculations should be time-zone independent then UTC (GMT) should be
the specified time zone.
Greg
On 2/28/06 10:44 PM, "Brett Powley" <email@hidden> wrote:
> Daylight savings perhaps? Summer DST began for the first time in the
> US on March 31 1918, which is right in the middle of where your
> weirdness happens...
>
> On 01/03/2006, at 10:06 AM, Ben Kazez wrote:
>
>> I have an application that retrieves an NSCalendarDate from a .ics
>> file and adds one year to it until the date is within a certain
>> range. (This isn't the most efficient way to do things, but it's
>> fast enough for my needs.) This algorithm runs into a problem with
>> dates before 1919. Here's the line that adds the date components:
>>
>> currentExpandedDate = [[IEPSystemCalendar
>> dateByAddingComponents:frequency toDate:currentExpandedDate options:
>> 0] dateWithCalendarFormat:BKWebScriptCalendarFormat timeZone:
>> [[unexpandedEvent objectForKey:@"DTSTART"] timeZone]];
>>
>> The frequency variable is set to one year using -[NSDateComponents
>> setYear:]. As an example, here the app is starting with 1914-03-01
>> 00:00:00 -0600:
>>
>> March 01, 1915 00:00:00
>> March 01, 1916 00:00:00
>> March 01, 1917 00:00:00
>> March 01, 1918 00:00:00
>> March 01, 1919 01:00:00
>> March 01, 1920 01:00:00
>> ...
>>
>> (Sorry for the inconsistent date formatting.) As you can see, after
>> 1918, the date is one hour off. Does anyone know why this is
>> happening?
>>
>> Ben
>
> --------------------------------------------------------------
> Brett Powley -- PhD Candidate
> Centre for Language Technology, Macquarie University, Australia
> p: +61-402-013050 f: +61-2-90120813 e: email@hidden
> faciendi plures libros nullus est finis
> frequensque meditatio carnis adflictio est
> --------------------------------------------------------------
>
>
>
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