当我想得到本周的星期日时的一个问题

Question

我编写这些代码是为了获得本周的星期日。

NSCalendar *cal = [NSCalendar currentCalendar];
NSDateComponents* components = [cal components: NSYearForWeekOfYearCalendarUnit | NSYearCalendarUnit | NSMonthCalendarUnit | NSWeekCalendarUnit | NSWeekdayCalendarUnit fromDate:[NSDate date]];

// I want to get the sunday
[components setWeekday:1];
NSDate* d = [cal dateFromComponents:components];
NSLog(@"Sunday:%@", d);

但我得到了结果：2012 年 2 月 25 日，我认为正确的结果应该是 2012 年 2 月 26 日。 它有什么问题？

Answer 1

你需要初始化更多的组件：

for (int i = 0; i < 12; i++)
{
    [components setWeek:i];
    [components setWeekday:1];
    d = [cal dateFromComponents:components];
    NSLog(@"Sunday,Week %d:%@", i,d);   
}

Output:

Sunday,Week 0:2011-12-25 08:00:00 +0000
Sunday,Week 1:2012-01-01 08:00:00 +0000
Sunday,Week 2:2012-01-08 08:00:00 +0000
Sunday,Week 3:2012-01-15 08:00:00 +0000
Sunday,Week 4:2012-01-22 08:00:00 +0000
Sunday,Week 5:2012-01-29 08:00:00 +0000
Sunday,Week 6:2012-02-05 08:00:00 +0000
Sunday,Week 7:2012-02-12 08:00:00 +0000
Sunday,Week 8:2012-02-19 08:00:00 +0000
Sunday,Week 9:2012-02-26 08:00:00 +0000
Sunday,Week 10:2012-03-04 08:00:00 +0000
Sunday,Week 11:2012-03-11 08:00:00 +0000