Locale query
I have an app that must process sqlite hosted data that contains Gregorian UTC dates. I want to ignore the local locale entirely and use Gregorian UTC through out. At present I am carefully configuring all my NSDatePickers controls and all NSDateComponents calculations to use a specified Gregorian UTC timezoned calendar. Is this the best I can do, or am I missing a trick somewhere? .NET has the concept of a thread culture that defines this sort of thing for a given thread.. Thanks Jonathan ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Locale query
> On 13 Nov 2014, at 15:23, John Joyce wrote:
>
>
>> On Nov 13, 2014, at 9:54 PM, Jonathan Mitchell
>> wrote:
>>
>> I have an app that must process sqlite hosted data that contains Gregorian
>> UTC dates.
>> I want to ignore the local locale entirely and use Gregorian UTC through out.
>>
>> At present I am carefully configuring all my NSDatePickers controls and all
>> NSDateComponents calculations to use a specified Gregorian UTC timezoned
>> calendar.
>>
>> Is this the best I can do, or am I missing a trick somewhere?
>>
>> .NET has the concept of a thread culture that defines this sort of thing for
>> a given thread..
>>
>> Thanks
>>
>> Jonathan
>>
> If you want to present things to users well, it is generally easier for
> people to think in their own locale.
> Better to calculate than they have to think about the difference.
> If the user story is one where they would actively think in Gregorian UTC,
> then it could be reasonable to do what you’re doing.
I think this is the case here.
The app performs financial calculations that are valid in one timezone.
If the user locates to a different timezone the apps calculations must still
reference the initial timezone.
Failure to do this causes miscalculation.
> There are lots of conveniences added in the 10.9 SDK for calendrical
> calculation, and in general, it is easier for all to work in
> NSDate/NSTimeInterval (time since reference date) for calculation and then
> use locales for presentation.
> In this case you might consider the DB to be another user of sorts that needs
> its locale to be Gregorian UTC, so your work all happens in the intermediary
> form and humans and the DB get the locale they like to use.
> If you have the calendar and time zone, the dates are easier to covert to the
> non-locale form and that is easy to convert to any locale. (and vice versa).
> Or did I misunderstand something?
I don’t think so.
I was running into problems using the local locale (which utilises british
summer time) when computing the number of days between dates (I use the
NSCalendar category method shown below).
I suppose the question is equivalent to asking if it is possible to configure
an individual app to return a predefined NSCalendar instance for [NSCalendar
currentCalendar] (I severely doubt this is possible).
This would prevent me from introducing bugs by forgetting to configure my
NSDatePicker s correctly etc.
Thanks
Jonathan
- (NSInteger)daysWithinEraFromDate:(NSDate *) startDate toDate:(NSDate *)
endDate
{
NSInteger startDay=[self ordinalityOfUnit:NSDayCalendarUnit
inUnit: NSEraCalendarUnit
forDate:startDate];
NSInteger endDay=[self ordinalityOfUnit:NSDayCalendarUnit
inUnit: NSEraCalendarUnit forDate:endDate];
// note call ABS() for absolute difference
return endDay-startDay;
}
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Re: Locale query
You could subclass NSDatePicker and have the subclass always set the
configuration the way you need it. It's just an NSControl, its only designated
initializer is initWithFrame:
On Nov 13, 2014, at 7:51 AM, Jonathan Mitchell wrote:
>
>> On 13 Nov 2014, at 15:23, John Joyce wrote:
>>
>>
>>> On Nov 13, 2014, at 9:54 PM, Jonathan Mitchell
>>> wrote:
>>>
>>> I have an app that must process sqlite hosted data that contains Gregorian
>>> UTC dates.
>>> I want to ignore the local locale entirely and use Gregorian UTC through
>>> out.
>>>
>>> At present I am carefully configuring all my NSDatePickers controls and all
>>> NSDateComponents calculations to use a specified Gregorian UTC timezoned
>>> calendar.
>>>
>>> Is this the best I can do, or am I missing a trick somewhere?
>>>
>>> .NET has the concept of a thread culture that defines this sort of thing
>>> for a given thread..
>>>
>>> Thanks
>>>
>>> Jonathan
>>>
>> If you want to present things to users well, it is generally easier for
>> people to think in their own locale.
>> Better to calculate than they have to think about the difference.
>> If the user story is one where they would actively think in Gregorian UTC,
>> then it could be reasonable to do what you’re doing.
> I think this is the case here.
> The app performs financial calculations that are valid in one timezone.
> If the user locates to a different timezone the apps calculations must still
> reference the initial timezone.
> Failure to do this causes miscalculation.
>
>> There are lots of conveniences added in the 10.9 SDK for calendrical
>> calculation, and in general, it is easier for all to work in
>> NSDate/NSTimeInterval (time since reference date) for calculation and then
>> use locales for presentation.
>> In this case you might consider the DB to be another user of sorts that
>> needs its locale to be Gregorian UTC, so your work all happens in the
>> intermediary form and humans and the DB get the locale they like to use.
>> If you have the calendar and time zone, the dates are easier to covert to
>> the non-locale form and that is easy to convert to any locale. (and vice
>> versa).
>> Or did I misunderstand something?
>
> I don’t think so.
> I was running into problems using the local locale (which utilises british
> summer time) when computing the number of days between dates (I use the
> NSCalendar category method shown below).
>
> I suppose the question is equivalent to asking if it is possible to configure
> an individual app to return a predefined NSCalendar instance for [NSCalendar
> currentCalendar] (I severely doubt this is possible).
> This would prevent me from introducing bugs by forgetting to configure my
> NSDatePicker s correctly etc.
>
> Thanks
>
> Jonathan
>
> - (NSInteger)daysWithinEraFromDate:(NSDate *) startDate toDate:(NSDate *)
> endDate
> {
>NSInteger startDay=[self ordinalityOfUnit:NSDayCalendarUnit
> inUnit: NSEraCalendarUnit
> forDate:startDate];
>NSInteger endDay=[self ordinalityOfUnit:NSDayCalendarUnit
> inUnit: NSEraCalendarUnit
> forDate:endDate];
>
>// note call ABS() for absolute difference
>return endDay-startDay;
> }
>
>
>
>
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