在Objective-C中解析简单的XML

Question

我从Web服务器返回了以下非常简单的XML,我使用ASIHttpRequest连接到:

<element1>something</element1>
<element2>somethingelse</element2>
<element3>anotherthing</element3>

ASIHttpRequest可以将其作为NSData或NSString返回.我需要解析信息,最简单的方法是什么？

谢谢

Answer 1

有一些XML解析器可用于iOS NSXMLParser,libxml2(DOM和SAX),TBXML,KissXML.您可以参考http://www.raywenderlich.com/553/how-to-chose-the-best-xml-parser-for-your-iphone-project来选择最佳的XML解析器(速度和内存占用).最简单的是TBXML.NSXMLParser也很简单.

NSXMLParser* xmlParser = [[NSXMLParser alloc] initWithData:receivedXMLData];//init NSXMLParser with receivedXMLData
[xmlParser setDelegate:self]; // Set delegate for NSXMLParser
[xmlParser parse]; //Start parsing
[xmlParser release];

//Delegate Methods
//Have a instance variable NSMutableString* currentString; to hold data between elements and NSMutableArray* elementsArray; to hold parsed data

- (void)parserDidStartDocument:(NSXMLParser *)parser
{
    elementsArray = [[NSMutableArray alloc] init];
}

//store all found characters between elements in currentString mutable string
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
    if(!currentString)
    {
        currentString = [[NSMutableString alloc] init];
    }
    [currentString appendString:string];    
}

//When end of XML tag is found this method gets notified
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
    if([elementName isEqualToString:@"element1"])
    {
        [elementsArray addObject:currentString];
        [currentString release],currentString=nil;
        return;
    }
    if([elementName isEqualToString:@"element2"])
    {
        [elementsArray addObject:currentString];
        [currentString release],currentString=nil;
        return;
    }
    if([elementName isEqualToString:@"element3"])
    {
        [elementsArray addObject:currentString];
        [currentString release],currentString=nil;
        return;
    }
    [currentString release],currentString =nil;
}

//Parsing has ended
- (void)parserDidEndDocument:(NSXMLParser *)parser
{
    NSLog(@"Content of Elements Array: %@",elementsArray);
        [elementsArray release],elementsArray=nil;
}

- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError
{
    UIAlertView* parseErrorAlert = [[UIAlertView alloc] initWithTitle:@"Parse Error" message:[NString stringWithFormat:"%@",[parseError localizedDescription]] delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil];
    [parseErrorAlert show];
    [parseErrorAlert release];
}

您还有其他委托方法,如parseErrorOccured.请参阅http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSXMLParser_Class/Reference/Reference.html

对于TBXML:http ://tbxml.co.uk/TBXML/API.html更新:已实现的parseError委托方法和有效的xml示例XML您在代码中发布的不是有效的XML(您可以在线检查XML验证:http:// validator.w3.org/#validate_by_input)所以它会抛出一个parseError.以下是您发布的有效XML XML:

<?xml version="1.0"?>
<root>
 <element1>something</element1>
 <element2>somethingelse</element2>
 <element3>anotherthing</element3>
</root>