NSCalendar，为什么设置firstWeekday不影响计算结果？ [英] NSCalendar, why does setting the firstWeekday doesn't effect calculation outcome?

问题描述

我需要计算给定日期的工作日，但是，根据每周一周的星期几和星期日的星期一星期日

i need to calculate the weekday for a given date, however, depending on the calendar a week can star on Monday and somwhere on Sunday

，我想设置周一开始使用

so i wanted to set it, to start on Monday, using

[[NSCalendar currentCalendar] setFirstWeekday:2];

但是，计算结果是相同的

however, the calculation outcome is the same

{
    [[NSCalendar currentCalendar] setFirstWeekday:1];
    NSDateComponents *weekdayComponents = [[NSCalendar currentCalendar] components:(NSDayCalendarUnit | NSWeekdayCalendarUnit) fromDate:date];
    NSInteger weekday = [weekdayComponents weekday] - 1;
    NSLog(@"%d", weekday);
}
{
    [[NSCalendar currentCalendar] setFirstWeekday:2];
    NSDateComponents *weekdayComponents = [[NSCalendar currentCalendar] components:(NSDayCalendarUnit | NSWeekdayCalendarUnit) fromDate:date];
    NSInteger weekday = [weekdayComponents weekday] - 1;
    NSLog(@"%d", weekday);
}

返回相同的数字，但是为什么？

returns same numbers, but why?

推荐答案

您看到的行为是正确的。 weekday组件不受firstWeekday属性的影响。如果你有一个日期代表星期天，它将永远是一个星期天潮湿你开始你的星期星期天或星期一。这应该影响是您的日期组件的周属性中的周数。

The behavior you see is correct. The weekday component is not affected by the firstWeekday property. If you have a date representing a sunday it will always be a sunday wether you start your week on that sunday or on monday. What this should affect is the week number in the week property of your date components.

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