从Cocoa中解析一个简单的XML字符串？ [英] Parsing a simple XML from string in Cocoa?

问题描述

我有一个简单的XML，我需要从puid-list中获取第一 id 。我发现了很多例子，但没有一个是因为命名空间。

PS：我如何将 ID m。Mac

 < genpuid songs =1xmlns：mip =http://musicip.com/ ns / mip-1.0＃> 
< track file =/ htdocs / test.mp3puid =0c9f2f0e-e72a-c461-9b9a-e18e8964ca20> 
< puid-list> 
< puid id =0c9f2f0e-e72a-c461-9b9a-e18e8964ca20/> 
< / puid-list> 
< / track> 
< / genpuid> 
  

解决方案

您应该使用 NSXMLParser 。在代码中创建一个实例，并让它解析：

  NSData * XMLData = [myXMLString dataUsingEncoding：NSUnicodeStringEncoding]; 
 NSXMLParser * parser = [[NSXMLParser alloc] initWithData：XMLData]; 
 [parser setDelegate：self]; 
 [parser setShouldProcessNamespaces：YES]; //如果你需要
 [parser parse]; //开始解析
  

那么你需要实现 NSXMLParserDelegate 在解析期间获取回调：

   - （void）parser：（NSXMLParser *）parser didStartElement： *）elementName 
 namespaceURI：（NSString *）namespaceURI qualifiedName：（NSString *）qualifiedName 
 attributes：（NSDictionary *）attributeDict {
 
 / / 
 
 if（[elementName isEqualToString：@puid]）{
 NSString * ID = [attributeDict objectForKey：@id]; 
 //使用ID字符串，或将其存储在一个ivar中，以便您可以访问它在其他地方
} 
} 
  

处理命名空间的注意事项：

如果设置命名空间， elementName 是限定名，所以可以有前缀（例如 mip：puid ）如果你在Mac上， NSXMLNode 有方便类的方法， localNameForName：和 prefixForName：得到字符串的两个部分。 p>

此外，您可能需要 NXXMLParser 委托方法 parser：didStartMappingPrefix：toURI：和 parser：didEndMappingPrefix：。

注意 NSXMLParser 是那些从字符串（关于它们是否带有前缀）。因此，属性很少被命名为 mip：id ，但如果你想要健壮，你还需要检查这个。

I have a simple XML and I need to get the first 'id' from puid-list. I found lots of examples but none of them quite do that because of the namespace. How do get the id out as an NSString?

PS: I'm on a Mac.

<genpuid songs="1" xmlns:mip="http://musicip.com/ns/mip-1.0#">
  <track file="/htdocs/test.mp3" puid="0c9f2f0e-e72a-c461-9b9a-e18e8964ca20">
    <puid-list>
      <puid id="0c9f2f0e-e72a-c461-9b9a-e18e8964ca20"/>
    </puid-list>
  </track>
</genpuid>

解决方案

You should use NSXMLParser. Create an instance in your code and tell it to parse:

NSData * XMLData = [myXMLString dataUsingEncoding:NSUnicodeStringEncoding];
NSXMLParser * parser = [[NSXMLParser alloc] initWithData:XMLData];
[parser setDelegate:self];
[parser setShouldProcessNamespaces:YES]; // if you need to
[parser parse]; // start parsing

then you need to implement the methods of NSXMLParserDelegate to get callbacks during parsing:

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName
  namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName
    attributes:(NSDictionary *)attributeDict{

    /* handle namespaces here if you want */

    if([elementName isEqualToString:@"puid"]){
         NSString * ID = [attributeDict objectForKey:@"id"];
         // use ID string, or store it in an ivar so you can access it somewhere else
    }
}

Notes on handling namespaces:

If the namespaces are set, elementName is the qualified name, so could have prefix (e.g. mip:puid) If you're on the Mac, NSXMLNode has to convenience class methods, localNameForName: and prefixForName: to get the two parts of the string.

Also, You might want the NXXMLParser delegate methods parser:didStartMappingPrefix:toURI: and parser:didEndMappingPrefix:.

Note that names returned by NSXMLParser are exactly those from the string (regarding whether they're prefixed). So it's rare for the attribute to be named mip:id, but if you want to be robust, you need to check for this as well.

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