blocks|key|4658037|text|这不是你问题的确切答案，但是当我想要解析日期而不确定格式时，我通常只为日期设置NSDataDetector。检测器通常会检测多种语言的日期，并一次性格式化所有日期。它相当整洁。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4658038|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

This is not exactly the answer to your question but when I'm looking to parse dates without being sure of the format I usually go for NSDataDetector setup for dates only. The detector will often detect dates in multiple languages and format all at once. It's pretty neat.

blocks|key|2087269|text|好的，谢谢你的评论。我最终做的是去http://waracle.net/iphone-nsdateformatter-date-formatting-table/，非常仔细地研究所有的NSDateFormatter选项。特别是RSS帖子末尾的%2B0000时区把我的格式转换搞得一团糟。RSS日期与RFC822匹配，这意味着您需要在末尾使用三个Z才能正确地捕获它。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2087270|我正在尝试像%2BZZZZ这样的东西，它们在字符串上失败了。这就是我之前修剪弦的原因。最终起作用的是：|2087271|@"Wed，17+Jul+2013+03:23:18+%2B0000“|2087272|需要以下格式化程序：|2087273|@"EEE，dd+MMM+yyyy+HH:mm:ss+ZZZ“|2087274|在为这种情况正确地设置了DateFormatter之后，我可以很容易地为其他格式找出其他格式。原来项目中只使用了3种不同的日期格式，我可以很容易地将正确的日期格式字符串与每个数据源一起存储，并在需要时将其插入到日期格式化程序中。不再需要字符串搜索，所有数据都会干净地转换为正确的NSDate。|2087275|因此，答案是，创建一个可转换各种日期格式的示例项目，插入所需的日期格式，并正确使用DateFormatter代码。你的日期问题可能并不像你想象的那么糟糕，更好地理解它们可以让代码变得更干净。|2087276|使用下面的示例，如果格式字符串不正确，您将看到(null)。|2087277|#import+<Foundation/Foundation.h>

int+main(int+argc,+const+char+*+argv[])
{

++++@autoreleasepool+{
++++++++NSArray+*dateStrings+=+@[
+++++++++++++//+From+data+source+1.
++++++++++++@[@"2012-04-18",@"yyyy-MM-dd"],
++++++++++++//++From+data+source+2.
++++++++++++@[@"2012-04-19+18:29:35",@"yyyy-MM-dd+HH:mm:ss"],
++++++++++++@[@"2011-05-04+11:10:50",@"yyyy-MM-dd+HH:mm:ss"],
++++++++++++//+From+RSS+feeds+(pubDate)
++++++++++++@[@"Wed,+17+Jul+2013+02:24:23+%2B0000",@"EEE,+dd+MMM+yyyy+HH:mm:ss+ZZZ"],
++++++++++++@[@"Tue,+25+Jun+2013+15:04:49+%2B0000",@"EEE,+dd+MMM+yyyy+HH:mm:ss+ZZZ"]
+++++++++++++++++++++++++++++++++];
++++++++NSDateFormatter+*formatter+=+[[NSDateFormatter+alloc]+init];
++++++++for(NSArray+*datePair+in+dateStrings){
++++++++++++[formatter+setDateFormat:datePair[1]];
++++++++++++NSDate+*thisDate+=+[formatter+dateFromString:datePair[0]];
++++++++++++[formatter+setDateStyle:NSDateFormatterMediumStyle];
++++++++++++NSLog(@"%25@+=+%25@",datePair[0],[formatter+stringFromDate:thisDate]);
++++++++}

++++}
++++return+0;
}|code-block|syntax|javascript|2087278|entityMap|0|LINK|mutability|MUTABLE|url|http://waracle.net/iphone-nsdateformatter-date-formatting-table/^0|H|1S|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@$A|15|B|16|1|17]]|C|$]]|$1|D|3|E|5|6|7|18|8|@]|9|@]|C|$]]|$1|F|3|G|5|6|7|19|8|@]|9|@]|C|$]]|$1|H|3|I|5|6|7|1A|8|@]|9|@]|C|$]]|$1|J|3|K|5|6|7|1B|8|@]|9|@]|C|$]]|$1|L|3|M|5|6|7|1C|8|@]|9|@]|C|$]]|$1|N|3|O|5|6|7|1D|8|@]|9|@]|C|$]]|$1|P|3|Q|5|6|7|1E|8|@]|9|@]|C|$]]|$1|R|3|S|5|T|7|1F|8|@]|9|@]|C|$U|V]]|$1|W|3|-4|5|6|7|1G|8|@]|9|@]|C|$]]]|X|$Y|$5|Z|10|11|C|$12|13]]]]

Okay thanks for the comments. What I ended up doing is going to <a href="http://waracle.net/iphone-nsdateformatter-date-formatting-table/" rel="nofollow">http://waracle.net/iphone-nsdateformatter-date-formatting-table/</a> and studying VERY CAREFULLY all the NSDateFormatter options. In particular it was the time zone +0000 at the end of RSS posts which was messing up my format conversions. RSS dates match RFC 822, which means you need to use THREE Z's at the end to properly catch it.

I was attempting things like +ZZZZ which were failing on the strings. That's why I was trimming the strings before. What ended up working was this: 
@"Wed, 17 Jul 2013 03:23:18 +0000" 
Needs formatter of:
@"EEE, dd MMM yyyy HH:mm:ss ZZZ"

After having correctly set up the DateFormatter for this case I was easily able to figure out others for the other formats. It turns out there's only 3 different date formats being used in the projects and I can easily store the right date format string along side each data source and plug that into the date formatter when needed. No more string searching needed and all data is cleanly converting to the correct NSDate. 

So the answer is, make a sample project that converts various date formats, plug in the ones you need and use the DateFormatter codes correctly. Chances are your date problems aren't as bad as you think and a better understanding of them can lead to cleaner code.

Using my example below you will see (null) if your format string is incorrect.

<pre><code>#import &lt;Foundation/Foundation.h&gt;

int main(int argc, const char * argv[])
{

 @autoreleasepool {
 NSArray *dateStrings = @[
 // From data source 1.
 @[@"2012-04-18",@"yyyy-MM-dd"],
 // From data source 2.
 @[@"2012-04-19 18:29:35",@"yyyy-MM-dd HH:mm:ss"],
 @[@"2011-05-04 11:10:50",@"yyyy-MM-dd HH:mm:ss"],
 // From RSS feeds (pubDate)
 @[@"Wed, 17 Jul 2013 02:24:23 +0000",@"EEE, dd MMM yyyy HH:mm:ss ZZZ"],
 @[@"Tue, 25 Jun 2013 15:04:49 +0000",@"EEE, dd MMM yyyy HH:mm:ss ZZZ"]
 ];
 NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
 for(NSArray *datePair in dateStrings){
 [formatter setDateFormat:datePair[1]];
 NSDate *thisDate = [formatter dateFromString:datePair[0]];
 [formatter setDateStyle:NSDateFormatterMediumStyle];
 NSLog(@"%@ = %@",datePair[0],[formatter stringFromDate:thisDate]);
 }

 }
 return 0;
}
</code></pre>

In dealing with a wide variety of JSON data being sent from various clients date format standardization is a real problem.

I might get any of these:
2013-10-05 
2-6-13 
Mon, Jul 13 2013 

Sometimes there's hours, minutes and seconds as well as time zone information. For each client I've had to manually set up an <code>NSDateFormatter</code>, or if unable to get it parsing I've done substring searching. What I'd really like to do is get all this combined into a single method and somehow determine which type I'm dealing with. Then have some kind of switch statement that handles the parsing for that particular date.

I'm unable to change their formats, but how can I deal with them better?

How can I determine which date format I've received?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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在处理从不同客户机发送的各种各样的JSON数据时，数据格式标准化是一个真正的问题。我可能会得到其中的任何一个: 2013-10-052-6-132013年7月13日星期一有时会有小时、分钟和秒以及时区信息。对于每个客户端，我必须手动设置一个NSDateFormatter，或者如果无法解析它，我会进行子字符串搜索。我真正...

问如何确定我收到了哪种日期格式？
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