在上午12:00动态创建上一个星期日的日期 [英] dynamically create date for previous sunday at 12:00 AM
问题描述
我正在努力弄清楚如何在上午12:00的最前一个星期日动态创建一个日期对象
I'm struggling to figure out how to dynamically create a date object for the most previous sunday at 12:00 AM
我以为我今天可以得到日期然后减去当周的当天+ 1,此时我可以减去当天的时间到达上午12点。
I was thinking I could get today's date and then subtract the current day of the week + 1 at which point I could just subtract the time of the day do get down to 12AM.
到目前为止,我有当前的星期几:
so far I have the current day of the week:
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *comps = [gregorian components:NSWeekdayCalendarUnit fromDate:[NSDate date]];
int weekday = [comps weekday];
此时我可以获得今天的日期并减去工作日的差异
一天中的*秒。但是,我怎样才能在几秒钟内获得今天的时间?
at which point I can get today's date and subtract the difference of weekday
* seconds in a day. However, how can I get today's time in seconds ??
推荐答案
无需手动计算秒数(这无论如何都是危险的夏令时等)。以下内容应该完全符合您的要求:
No need to manually calculate seconds (which is dangerous anyway because of daylight saving etc.). The following should do exactly what you want:
NSDate *today = [NSDate date];
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[calendar setLocale:[[NSLocale alloc] initWithLocaleIdentifier:@"en-US"]]; // force US locale, because other countries (e.g. the rest of the world) might use different weekday numbering
NSDateComponents *nowComponents = [calendar components:NSYearCalendarUnit | NSWeekCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit fromDate:today];
[nowComponents setWeekday:1]; //Sunday
[nowComponents setHour:0]; // 12:00 AM = midnight (12:00 PM would be 12)
[nowComponents setMinute:0];
[nowComponents setSecond:0];
NSDate *previousSunday = [calendar dateFromComponents:nowComponents];
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