NSDateComponents 在 1970 年 1 月 1 日返回第 53 周

发布于 2024-11-16 13:55:43 字数 709 浏览 3 评论 0原文

因此，当使用 NSCalendar 和 NSDateComponents 从 NSDate 对象中提取日期组件时，我遇到了一个奇怪的行为。如果日期距离 1970 年 0 秒，周部分将返回 53。除了模数 52 的明显方法之外，是否有对此的解释或解决方法？

这是您可以在计算机上运行来测试的代码：

 (void)testDate {
    NSCalendar *cal = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSDate *date = [NSDate dateWithTimeIntervalSince1970:0];
    NSDateComponents *comp = [cal components:(NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit | NSWeekCalendarUnit) fromDate:date];
    DLog(@"%d/%d/%d week: %d", [comp day],[comp month], [comp year], [comp week]);

}

这是输出：

31/12/1969 week: 53
(gdb) po date
1970-01-01 00:00:00 +0000
(gdb)

原文

So when extracting the dates components from NSDate object using NSCalendar and NSDateComponents I encountered a weird behavior.
If the date is 0 sec from 1970 the week component will return 53.
Is there an explination for this or a way to fix other than the obvious way of modulus 52?

here is the code you can run on your machine to test:

 (void)testDate {
    NSCalendar *cal = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSDate *date = [NSDate dateWithTimeIntervalSince1970:0];
    NSDateComponents *comp = [cal components:(NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit | NSWeekCalendarUnit) fromDate:date];
    DLog(@"%d/%d/%d week: %d", [comp day],[comp month], [comp year], [comp week]);

}

and here is the output:

31/12/1969 week: 53
(gdb) po date
1970-01-01 00:00:00 +0000
(gdb)

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北笙凉宸 2024-11-23 13:55:43

好吧，我明白了，

2011-06-22 22:38:50.516 SmallTasks[23164:903] 1/1/1970 week: 1

所以我对你得到的结果有点惊讶，但我对 week: 53 结果为 52 * 7 = 364 并不感到惊讶，我们一年有365天。为了实现这一点，我预计这一周会从 1969 年的星期日开始，但事实并非如此。

Well I got this,

2011-06-22 22:38:50.516 SmallTasks[23164:903] 1/1/1970 week: 1

So I am bit surprised by the result you got but I am not that surprised that a week: 53 turned up as 52 * 7 = 364 and we've 365 days in a year. For that to happen I would expect the week to start on Sunday on 1969 but it didn't.

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