objective-c - 在 NSXMLParser 中解析 xml

Question

我已经阅读了许多关于如何从 xml 文件中获取文本的示例，但就是不知道如何操作。这是一个示例 xml 文件:

<?xml version="1.0" encoding="UTF-8"?>
<questions>
    <set>
        <question>Question</question>
        <answer>Answer</answer>
    </set>
</questions>

使用 -(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI，获取值的最简单方法是什么问题 和 Answer？我已经连接上了我的解析器代理和所有这些废话。

Answer 1

要实现 NSXMLParser，您需要实现它的委托(delegate)方法。

首先以这种方式启动NSXMLParser。

- (void)viewDidLoad {

    [super viewDidLoad];

    rssOutputData = [[NSMutableArray alloc]init];

    //declare the object of allocated variable
    NSData *xmlData=[[NSData alloc]initWithContentsOfURL:[NSURL URLWithString:@""]];// URL that given to parse.

    //allocate memory for parser as well as 
    xmlParserObject =[[NSXMLParser alloc]initWithData:xmlData];
    [xmlParserObject setDelegate:self];

    //asking the xmlparser object to beggin with its parsing
    [xmlParserObject parse];

    //releasing the object of NSData as a part of memory management
    [xmlData release];

}
//-------------------------------------------------------------


-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *) namespaceURI qualifiedName:(NSString *)qName
   attributes: (NSDictionary *)attributeDict
{
    if( [elementName isEqualToString:@"question"])
    {

         strquestion = [[NSMutableString alloc] init];

    }
}


//-------------------------------------------------------------


-(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
       // init the ad hoc string with the value     
     currentElementValue = [[NSMutableString alloc] initWithString:string];
  } else {
     // append value to the ad hoc string    
    [currentElementValue appendString:string];
  }
  NSLog(@"Processing value for : %@", string);
}


//-------------------------------------------------------------


-(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
    if( [elementName isEqualToString:@"question"])
    {
        [strquestion setString:elementName];
    }

 [currentElementValue release];
  currentElementValue = nil;
}

上述委托(delegate)方法由解析器对象在遇到特定元素的结尾时发送给它的委托(delegate)。在此方法 didEndElement 中，您将获得 question 的值。