objective-c XML解析

最近项目用到了从服务器获取xml文件，需要解析xml来获取数据，下面简单举个例子，以便自己以后学习并复习。另外http://www.w3school.com.cn/xpath/xpath_examples.asp上有一些例子，有兴趣的同学可以去看看xml的相关知识。

从服务器上下载的xml文件：

<?xml version="1.0" encoding="utf-8"?>
<page>
	<ROWSET>
		<ROW num="1"><!--   订单1  -->
			<ORDERNO>C1007260000037</ORDERNO><!--   订单号，选填  -->
			<STATUS>E</STATUS><!--   订单状态  -->
			<TOTALPAYMONEY>6810</TOTALPAYMONEY><!--   订单总价  -->
			<CREATEDATE>2010-07-26</CREATEDATE><!--   订单创建日期  -->
			<CAMPAIGNSCRIPTID>6</CAMPAIGNSCRIPTID><!--  订单类型标识  -->
			<SEGINFO><!--   订单航段  -->
				<SEGINFO_ROW num="1"><!--   订单航段1  -->
					<CARRIER>CZ</CARRIER>
					<DEPCODE>CAN</DEPCODE>
					<ARRCODE>PEK</ARRCODE>
					<DEPPORT> 广州</DEPPORT>
					<ARRPORT> 北京</ARRPORT>
					<CARRIER>CZ</CARRIER>
					<FLIGHTNO>3107</FLIGHTNO>
					<DEPTIME>2010-07-28</DEPTIME>
					<ARRTIME>2010-07-28</ARRTIME>
				</SEGINFO_ROW>
				<SEGINFO_ROW num="2"><!--   订单航段2  -->
					<CARRIER>CZ</CARRIER>
					<DEPCODE>PEK</DEPCODE>
					<ARRCODE>CAN</ARRCODE>
					<DEPPORT> 北京</DEPPORT>
					<ARRPORT> 广州</ARRPORT>
					<CARRIER>CZ</CARRIER>
					<FLIGHTNO>3104</FLIGHTNO>
					<DEPTIME>2010-07-29</DEPTIME>
					<ARRTIME>2010-07-29</ARRTIME>
				</SEGINFO_ROW>
			</SEGINFO>
		</ROW>
		<ROW num="2">
			<ORDERNO>C1007260000034</ORDERNO>
			<DOMESTICINDICATE>1</DOMESTICINDICATE>
			<STATUS>C</STATUS>
			<TOTALPAYMONEY>2010</TOTALPAYMONEY>
			<CREATEDATE>2010-07-26</CREATEDATE>
			<CAMPAIGNSCRIPTID>6</CAMPAIGNSCRIPTID>
			<SEGINFO>
				<SEGINFO_ROW num="1">
					<CARRIER>CZ</CARRIER>
					<DEPCODE>CAN</DEPCODE>
					<ARRCODE>PEK</ARRCODE>
					<DEPPORT> 广州</DEPPORT>
					<ARRPORT> 北京</ARRPORT>
					<CARRIER>CZ</CARRIER>
					<FLIGHTNO>3107</FLIGHTNO>
					<DEPTIME>2010-07-28</DEPTIME>
					<ARRTIME>2010-07-28</ARRTIME>
				</SEGINFO_ROW>
			</SEGINFO>
		</ROW>
	</ROWSET>
</page>

上面的xml中主要需要两个循环，一个：ROWSET下的ROW节点 ，一个是：SEGINFO下的SEGINFO_ROW节点
UserOrder *orderObj 自己定义的数据结构，用来存放xml数据

//初始化数据源，从(NSData*)aData参数中
GDataXMLDocument *doc = [[GDataXMLDocument alloc] initWithData:aData options:0 error:&error];

NSMutableArray *orderArray = [[NSMutableArray alloc] initWithCapacity:2];
    
    NSArray *orders = [doc nodesForXPath:@"//ROW" error:aError];//循环ROW节点
    for (GDataXMLElement *order in orders) {
        
        UserOrder *orderObj = [[UserOrder alloc] init];
        
//获取ROW节点下节点数据
        orderObj.orderNo = [order stringForTextNodeNamed:@"ORDERNO"];
        orderObj.status = [order stringForTextNodeNamed:@"STATUS"];
        orderObj.price = [order stringForTextNodeNamed:@"TOTALPAYMONEY"];
        orderObj.date = [order stringForTextNodeNamed:@"CREATEDATE"];
        orderObj.orderType = [order stringForTextNodeNamed:@"CAMPAIGNSCRIPTID"];
        
        
        NSArray *segmentElementArray = [order nodesForXPath:@"SEGINFO/SEGINFO_ROW" error:aError];//循环SEGINFO_ROW节点
        if (segmentElementArray != nil) {
            
            for (GDataXMLElement *segmentElement in segmentElementArray) {
                
                OrderSegment *segment = [[OrderSegment alloc] init];
                
//获取SEGINFO_ROW节点下数据
                segment.carrier = [segmentElement stringForTextNodeNamed:@"CARRIER"];
                segment.flightType = [segmentElement stringForTextNodeNamed:@"FLIGHTNO"];
                segment.depCode = [segmentElement stringForTextNodeNamed:@"DEPCODE"];
                segment.arrCode = [segmentElement stringForTextNodeNamed:@"ARRCODE"]; 
                segment.depPort = [segmentElement stringForTextNodeNamed:@"DEPPORT"];
                segment.arrPort = [segmentElement stringForTextNodeNamed:@"ARRPORT"];
                segment.flightNo = [segmentElement stringForTextNodeNamed:@"FLIGHTNO"];
                segment.depTime = [segmentElement stringForTextNodeNamed:@"DEPTIME"];
                segment.arrTime = [segmentElement stringForTextNodeNamed:@"ARRTIME"];
                
                [orderObj.segments addObject:segment];
                [segment release];
                
            }
            
            [orderArray addObject:orderObj];
        }
        [orderObj release];
        
    }
    return [orderArray autorelease];//返回数据