首页 文章

NSDateComponents将UTC日期转换为本地时区，弄乱了“今天”的nsdate比较

提问于
浏览 次
2

我正在尝试使用NSDateComponents来测试动态日期是否“今天” . 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 date]：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小时偏移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的：

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

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
}
ios objective-c timezone nsdate nsdatecomponents

1 回答

  • 4

    您正在更改 NSDateComponents 的时区 . 但是你想在调用 components （或调用 NSCalendar 天检查例程）之前更改日历的时区，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） . 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，那么你真的说你想使用 _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");
}
    回复于

相关问题