NSDateComponents组件：fromDate和Time Zones [英] NSDateComponents components:fromDate and Time Zones

问题描述

我有一种方法，通过将其分解为NSDateComponents，将小时和秒组件从NSDate中提取出来。我的代码如下...

I have a method which extracts the hour and second components form a NSDate by breaking it down into its NSDateComponents. My code is as follows...

unsigned hourAndMinuteFlags = NSHourCalendarUnit | NSMinuteCalendarUnit;
NSCalendar* calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[calendar setTimeZone:[NSTimeZone timeZoneWithName:@"GMT"]];
NSDateComponents* travelDateTimeComponents = [calendar components:hourAndMinuteFlags fromDate:travelDate];
NSString* hours = [NSString stringWithFormat:@"%02i", [travelDateTimeComponents hour]];
NSString* minutes = [NSString stringWithFormat:@"%02i", [travelDateTimeComponents minute]];

我的问题是我在转换中损失了一个小时。我怀疑它是由时区引起的，但据我所知，日期传入和使用的日历都是GMT。

My problem is that I'm losing an hour in the conversion. I have a suspicion that it's due to timezones but as far as I can see both the date being passed in and the calendar being used are both GMT.

例如，如果我传入以下NSDate对象（这是[NSDate description]的日志）...

For example if I pass in the following NSDate object (this is a log of [NSDate description])...

2010-08-02 08:00:00 +0100

我希望我的小时数为8，分钟数为0，但我我的小时实际上回来了7。

I expect that I get 8 for hours and 0 for minutes, but I actually get back 7 for my hours.

我的系统时间是GMT，因此上面的NSDate目前是英国夏令时的+0100。

My system time is GMT, hence the NSDate above is currently +0100 for British Summer Time.

推荐答案

事情是，GMT不等于英国夏令时。日期 2010-08-02 08:00:00 +0100 等于 2010-08-02 07:00:00 GMT 所以你应该期待7个小时。

The thing is, GMT is not equal to British Summer Time. The date 2010-08-02 08:00:00 +0100 is equal to 2010-08-02 07:00:00 GMT so 7 hours is the result you should expect.

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