我如何使用NSDateFormatter有什么问题？ [英] What's wrong with how I'm using NSDateFormatter?

问题描述

   NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
   dateFormatter.locale = [[[NSLocale alloc] initWithLocaleIdentifier:@"en_US"] autorelease];
   [dateFormatter setDateFormat:@"EEE, d MMM yyyy HH:mm:ss zzz"];
   NSString *dateString = @"Tue, 08 Jun 2010 17:00:00 EDT";
   NSDate *eventDate = [dateFormatter dateFromString:dateString];

在这种情况下，eventDate对象为nil。有人能告诉我吗？此代码曾经有效。

In this case the eventDate object is nil. Can somebody clue me in? This code used to work.

更新：
无法谈论为什么由于NDA而无效。我只想说，当iOS 4出局时，我会将答案发给我自己的问题。

UPDATE: Can't talk about why this doesn't work due to NDA. Suffice it to say, when iOS 4 is out I will post the answer to my own question.

推荐答案

这个问题的答案如下：
我使用了错误的日期格式字符串：

The answer to this question is the following: I was using the wrong date format string:

@"EEE, d MMM yyyy HH:mm:ss zzz"

应该是：

@"EEE, dd MMM y HH:mm:ss zzz"

关于iOS 4和NDA的部分是我认为我必须使用 NSDateFormatter 方法 dateFormatFromTemplate：options：locale： 看起来像这样：

The part about iOS 4 and NDA was that I thought I had to use the NSDateFormatter method dateFormatFromTemplate:options:locale: which would have looked like this:

NSString *format = [NSDateFormatter dateFormatFromTemplate:@"EEE, d MMM yyyy HH:mm:ss zzz" options:0 locale:[NSLocale currentLocale]];

但是，只有在想要将日期显示给未知语言环境的用户时才应使用该方法。在我的情况下，我确切地知道日期格式是什么样的，我试图将日期字符串PARSE，以便我可以将它存储在CoreData中。因此，该方法无用。

However, that method should only be used when you want to DISPLAY the date to a user of unknown locale. In my case, I knew exactly what the date format was going to look like and I was trying to PARSE the date string so that I could store it in CoreData. Therefore, that method wasn't useful.

奖励书签：仔细阅读此表，您一定会弄清楚问题所在。 .. Unicode日期格式应遵循以下规范： http://unicode.org/reports /tr35/tr35-6.html#Date_Field_Symbol_Table

Bonus bookmark: Read this table very carefully and you will definitely figure out what the problem is... Unicode date formats should follow these specifications: http://unicode.org/reports/tr35/tr35-6.html#Date_Field_Symbol_Table

TL; DR 格式字符串错误。噢哦！

TL;DR The format string was wrong. D'oh!

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