[转载][iPhone]XML文件解析parsingxmlfilesNSXMLParser

For example, say you have a simple XML file such as the following:

The parser would report the following series of events to its delegate:

1. Started parsing document

2. Found start tag for element article &＃xff0d;&＃xff0d;&＃xff0d;

3. Found attribute author of element article, value “John Doe”&＃xff0d;&＃xff0d;&＃xff0d;&＃xff0d;&＃xff0d;author&＃61;"John Doe"

4. Found start tag for element para &＃xff0d;&＃xff0d;&＃xff0d;&＃xff0d;&＃xff0d;

5. Found characters &＃xff0d;&＃xff0d;&＃xff0d;&＃xff0d;&＃xff0d;&＃xff0d;This is a very short article. 【 element&＃39;s value】

6. Found end tag for element para&＃xff0d;&＃xff0d;&＃xff0d;&＃xff0d;&＃xff0d;&＃xff0d;para>

7. Found end tag for element article&＃xff0d;&＃xff0d;&＃xff0d;&＃xff0d;article>

8. Ended parsing document

使用NSXMLParser步骤方法如下&＃xff1a;

       步骤一&＃xff0c;确定从xml文件解析出来的数据如何保存&＃xff0d;&＃xff0d;定义一个类&＃xff08;结构体&＃xff09;

                     小提示&＃xff1a;可能一个xml文件解析出的数据包含多个对象&＃xff0c;可以用NSMutableArray来保存。如参考一中提到的books

   步骤二&＃xff0c;自定义解析处理方法&＃xff08;主要三个方法&＃xff09;&＃xff0d;&＃xff0d;Delegate代理

       为了使代码清晰 可以单独提出来作为一个类

方法一&＃xff1a;

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

if([elementName isEqualToString:&＃64;"Books"]) {
//Initialize the array.
appDelegate.books &＃61; [[NSMutableArray alloc] init];
}

aBook.bookID &＃61; [[attributeDict objectForKey:&＃64;"id"] integerValue];

}

方法二&＃xff1a;主要处理element&＃39;s value 主要一般都是如下处理保存value值到字符串

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

if(!currentElementValue)
currentElementValue &＃61; [[NSMutableString alloc] initWithString:string];
else
[currentElementValue appendString:string];

NSLog(&＃64;"Processing Value: %&＃64;", currentElementValue);

}

方法三&＃xff1a;

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

if([elementName isEqualToString:&＃64;"Book"]) {
[appDelegate.books addObject:aBook];

[aBook release];
aBook &＃61; nil;
}

}

    步骤三 获取xml文件&＃xff0c;并建立NSXMLParser对象&＃xff0c;后解析

如参考一中实例&＃xff0c;从url获取xml文件&＃xff0c;并实例化NSXMLParser对象

NSURL *url &＃61; [[NSURL alloc] initWithString:&＃64;"http://sites.google.com/site/iphonesdktutorials/xml/Books.xml"];
NSXMLParser *xmlParser &＃61; [[NSXMLParser alloc] initWithContentsOfURL:url];

//Initialize the delegate.实例化解析处理方法的代理&＃xff08;步骤二中定义的代理&＃xff09;
XMLParser *parser &＃61; [[XMLParser alloc] initXMLParser];

//Set delegate 设置NSXMLParser对象的解析方法代理
[xmlParser setDelegate:parser];

//Start parsing the XML file.调用代理解析NSXMLParser对象
BOOL success &＃61; [xmlParser parse];

if(success)
NSLog(&＃64;"No Errors");
else
NSLog(&＃64;"Error Error Error!!!");