Question

我正在尝试使用NSDateComponents来测试动态日期是否发生＆＃34;今天＆＃34;。我用它来提取年/月/日，然后比较两个NSDates的值。理论上这应该有效。我在东海岸，所以EST，-5来自UTC。

实际当前时间：美国东部时间12:40:53

以下是UTC中正确的NSDates。时间是正确的UTC：

当前[NSDate日期]：2016-01-19 17:40:53 +0000
活动NSDate：2016-01-19 00:00:00 +0000

这是我的日志，显示每个日期。它将日期转换为当地时区2016-01-19 07:00:00。由于当前日期是在当天中间，因此-5小时的偏移量不会导致它转移天数。然而午夜却转移到了一天。我怎样才能让它尊重UTC？

NSLog：

2016-1-19 12:40:53 (America/New_York (EST) offset -18000), 
2016-1-18 19:0:0 (America/New_York (EST) offset -18000)

代码：

NSDateComponents *current = [[NSCalendar currentCalendar] components:NSCalendarUnitEra | NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay |NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond |NSCalendarUnitTimeZone fromDate:_date];
NSDateComponents *activity = [[NSCalendar currentCalendar] components:NSCalendarUnitEra | NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay |NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond |NSCalendarUnitTimeZone fromDate:activityModel.date];

// attempt to set timezones to UTC manually, doesn't change anything   
activity.calendar = [NSCalendar currentCalendar];
activity.calendar.timeZone = [NSTimeZone timeZoneWithAbbreviation:@"UTC"];

current.calendar = [NSCalendar currentCalendar];
current.calendar.timeZone = [NSTimeZone timeZoneWithAbbreviation:@"UTC"];


NSLog(@"%ld-%ld-%ld %ld:%ld:%ld (%@), %ld-%ld-%ld %ld:%ld:%ld (%@)", (long)[current year],(long)[current month], (long)[current day], (long)[current hour], (long)[current minute], (long)[current second], [current timeZone].description, (long)[activity year], (long)[activity month], (long)[activity day],(long)[activity hour], (long)[activity minute], (long)[activity second],[current timeZone].description);

if([current day] == [activity day] &&
           [current month] == [activity month] &&
           [current year] == [activity year] &&
           [current era] == [activity era]) {

           // do something if activity on current day
}

Answer 1

您正在更改NSDateComponents的时区。但是，在调用components（或调用NSCalendar天检查例程）之前，您想要更改日历的时区，例如：

NSCalendar *calendar = [NSCalendar calendarWithIdentifier:NSCalendarIdentifierGregorian];
calendar.timeZone = [NSTimeZone timeZoneForSecondsFromGMT:0];

if ([calendar isDate:_date inSameDayAsDate:activityModel.date]) {
    NSLog(@"same");
} else {
    NSLog(@"diff");
}

但是如果当地时间是2016-01-19 21:00:00 -0500（即20日，UTC），该怎么办？您是否希望它表示它与您示例中的活动日期同一天？如果是这样，那么你真的说你要使用_date的本地日历和activityModel.date的UTC，例如：

NSCalendar *calendar = [NSCalendar calendarWithIdentifier:NSCalendarIdentifierGregorian];

NSDateComponents *current = [calendar components:NSCalendarUnitEra | NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay |NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond |NSCalendarUnitTimeZone fromDate:_date];

calendar.timeZone = [NSTimeZone timeZoneForSecondsFromGMT:0];

NSDateComponents *activity = [calendar components:NSCalendarUnitEra | NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay |NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond |NSCalendarUnitTimeZone fromDate:activityModel.date];

if ([current day] == [activity day] && [current month] == [activity month] && [current year] == [activity year] && [current era] == [activity era]) {
    NSLog(@"same");
} else {
    NSLog(@"diff");
}

NSDateComponents将UTC日期转换为本地时区，搞砸了＃34;今天＆＃34; nsdate比较

1 个答案: