NSDateFormatter 错误的日期 [英] NSDateFormatter wrong date
问题描述
就这么简单
NSDateFormatter *df = [[NSDateFormatter alloc] init];
[df setDateFormat:@"dd/MM/yyyy"];
NSLog(@"Current date in event %@ %@",currentDate,[df stringFromDate:currentDate]);
但是在日志中
Current date in event 2013-10-01 22:00:00 +0000 02/10/2013
为什么?
推荐答案
当您记录 NSDate
时,它总是以 UTC 时间打印.当您使用 stringFromDate:
时,除非您更改日期格式化程序的时区,否则您将获得本地时间的日期.
When you log an NSDate
it always prints in UTC time. When you use stringFromDate:
you get a date in local time unless you change the timezone of the date formatter.
在这种情况下,您所在的时区比 UTC 早两个小时(假设您在意大利).
In this case you are in a timezone two hours ahead of UTC (assuming you are in Italy).
由于 NSDate
对象是 2013 年 10 月 1 日 22:00 UTC,这与 2013 年 10 月 2 日午夜 UTC+2 相同.这就是为什么您会看到显示 10 月 2 日的字符串.
Since the NSDate
object is October 1, 2013 at 22:00 UTC, this is the same as midnight of October 2, 2013 at UTC+2. This is why you see the string showing October 2.
这是另一种看待它的方式.您没有看到 1 天的差异.由于您的时区,您实际上看到了 2 小时的差异.从您的时间午夜到 0200 小时,您会看到 1 天的差异.
Here's another way to look at it. You are not seeing a 1 day difference. You are actually seeing a 2 hour difference due to your timezone. From midnight to 0200 hours your time, you will see what appears to be a 1 day difference.
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