如何使用 NSXMLParser 解析同名的父子元素

Posted 2023-02-24

【中文标题】如何使用 NSXMLParser 解析同名的父子元素

【英文标题】：How to use NSXMLParser to parse parent-child elements that have the same name

【发布时间】：2011-01-01 14:29:53

【问题描述】：

有人知道如何使用事件驱动模型 NSXMLParser 类解析以下 xml 吗？

<Node>
  <name> Main </name>
  <Node>
    <name> Child 1 </name>
  </Node>

  <Node>
    <name> Child 2 </name>
  </Node>
</Node>

我想从这个 xml 文件中收集所有三个名称，是否可以，或者我必须更改为基于树的解析？

【参考方案1】：

对于短 XML 文件，比公认的答案更简单的解决方法：

XML 示例：

<cotacoes>
    <bovespa>
            <cotacao>50058</cotacao>
            <variacao>-0.16</variacao>
    </bovespa>
    <dolar>
            <cotacao>3.4610</cotacao>
            <variacao>+0.29</variacao>
    </dolar>
    <euro>
            <cotacao>3.7673</cotacao>
            <variacao>-0.25</variacao>
    </euro>
    <atualizacao>04/08/15 - 18:14</atualizacao>
</cotacoes>

实现一个计数器：

@implementation className
    int parserCounter;


- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string

    parserCounter++;

    NSLog(@"%d: %@",contadorParser,string);

    if (parserCounter == 3) doAnythingFor3;
    if (parserCounter == 5) doAnythingFor5;
    if (parserCounter == 9) doAnythingFor9;
    if (parserCounter == 11) doAnythingFor11;
    if (parserCounter == 15) doAnythingFor15;
    if (parserCounter == 17) doAnythingFor17;
    if (parserCounter == 20) doAnythingFor20;

我怎么知道女巫号码是女巫节点？ 通过查看日志。它会是这样的：

2015-08-04 23:36:08.070 Tesouro Direto[7252:1554402] 1:     
2015-08-04 23:36:08.070 Tesouro Direto[7252:1554402] 2:     
2015-08-04 23:36:08.071 Tesouro Direto[7252:1554402] 3:     50058
2015-08-04 23:36:08.105 Tesouro Direto[7252:1554402] 4:     
2015-08-04 23:36:08.105 Tesouro Direto[7252:1554402] 5:     -0.16
2015-08-04 23:36:08.131 Tesouro Direto[7252:1554402] 6:     
2015-08-04 23:36:08.132 Tesouro Direto[7252:1554402] 7:     
2015-08-04 23:36:08.132 Tesouro Direto[7252:1554402] 8:     
2015-08-04 23:36:08.132 Tesouro Direto[7252:1554402] 9:     3.4610
2015-08-04 23:36:08.156 Tesouro Direto[7252:1554402] 10:    
2015-08-04 23:36:08.156 Tesouro Direto[7252:1554402] 11:    +0.29   
2015-08-04 23:36:08.180 Tesouro Direto[7252:1554402] 12:    
2015-08-04 23:36:08.180 Tesouro Direto[7252:1554402] 13:    
2015-08-04 23:36:08.180 Tesouro Direto[7252:1554402] 14:    
2015-08-04 23:36:08.180 Tesouro Direto[7252:1554402] 15:    3.7673
2015-08-04 23:36:08.203 Tesouro Direto[7252:1554402] 16:    
2015-08-04 23:36:08.203 Tesouro Direto[7252:1554402] 17:    -0.25
2015-08-04 23:36:08.226 Tesouro Direto[7252:1554402] 18:    
2015-08-04 23:36:08.227 Tesouro Direto[7252:1554402] 19:    
2015-08-04 23:36:08.227 Tesouro Direto[7252:1554402] 20:    04/08/15   - 18:14
2015-08-04 23:36:08.227 Tesouro Direto[7252:1554402] 21: 

日志会显示每个节点的女巫编号。

【参考方案2】：

- (NSInteger)columnNumber

为您提供NSXMLParser 的嵌套级别

【参考方案3】：

这是“SAX 类型”解析器的常见问题，您必须手动跟踪您所在的 XML 树的当前深度。与往常一样，问题是加载内存中的 DOM 结构中的整个树可能是不可能的，具体取决于您要操作的数据的大小。

以下代码显示了一个完成这项工作的类：

#import <Foundation/Foundation.h>

@interface Test : NSObject <NSXMLParserDelegate> 

@private
    NSXMLParser *xmlParser;
    NSInteger depth;
    NSMutableString *currentName;
    NSString *currentElement;


- (void)start;

@end

这是实现：

#import "Test.h"

@interface Test ()
- (void)showCurrentDepth;
@end


@implementation Test

- (void)dealloc

    [currentElement release];
    [currentName release];
    [xmlParser release];
    [super dealloc];


- (void)start

    NSString *xml = @"<?xml version=\"1.0\" encoding=\"UTF-8\" ?><Node><name>Main</name><Node><name>Child 1</name></Node><Node><name>Child 2</name></Node></Node>";
    xmlParser = [[NSXMLParser alloc] initWithData:[xml dataUsingEncoding:NSUTF8StringEncoding]];
    [xmlParser setDelegate:self];
    [xmlParser setShouldProcessNamespaces:NO];
    [xmlParser setShouldReportNamespacePrefixes:NO];
    [xmlParser setShouldResolveExternalEntities:NO];
    [xmlParser parse];



#pragma mark -
#pragma mark NSXMLParserDelegate methods

- (void)parserDidStartDocument:(NSXMLParser *)parser 

    NSLog(@"Document started", nil);
    depth = 0;
    currentElement = nil;


- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError 

    NSLog(@"Error: %@", [parseError localizedDescription]);


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

    [currentElement release];
    currentElement = [elementName copy];

    if ([currentElement isEqualToString:@"Node"])
    
        ++depth;
        [self showCurrentDepth];
    
    else if ([currentElement isEqualToString:@"name"])
    
        [currentName release];
        currentName = [[NSMutableString alloc] init];
    


- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName 
  namespaceURI:(NSString *)namespaceURI 
 qualifiedName:(NSString *)qName


    if ([elementName isEqualToString:@"Node"]) 
    
        --depth;
        [self showCurrentDepth];
    
    else if ([elementName isEqualToString:@"name"])
    
        if (depth == 1)
        
            NSLog(@"Outer name tag: %@", currentName);
        
        else 
        
            NSLog(@"Inner name tag: %@", currentName);
        
    
        

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string

    if ([currentElement isEqualToString:@"name"]) 
    
        [currentName appendString:string];
     


- (void)parserDidEndDocument:(NSXMLParser *)parser 

    NSLog(@"Document finished", nil);


#pragma mark -
#pragma mark Private methods

- (void)showCurrentDepth

    NSLog(@"Current depth: %d", depth);


@end

这是运行触发上述“start”方法的命令行工具的结果：

Document started
Current depth: 1
Outer name tag: Main
Current depth: 2
Inner name tag: Child 1
Current depth: 1
Current depth: 2
Inner name tag: Child 2
Current depth: 1
Current depth: 0
Document finished

【讨论】：

感谢您的解决方案，它对我来说很好用。 xml 文件很长，我已将其缩小以适应问题。