現(xiàn)在開發(fā)大多數(shù)時候都是通過json數(shù)據(jù)進(jìn)行服務(wù)器與客戶端的數(shù)據(jù)傳輸，但有時候也會遇到利用XML字符串進(jìn)行交互的情況，本文將對這一功能進(jìn)行基礎(chǔ)講解。

1.準(zhǔn)備

• 下載第三方庫，將GDataXMLNode導(dǎo)入到工程里。
• 在Xcode－－>Build Phases－－>Link Binary With Libraries里面添加libxml2.tbd
• 在Xcode－－>Build Phases－－>Complie Sources里面找到GDataXMLNode.m，雙擊Complier Flag區(qū)域，添加-fno-objc-arc字段
• 在Xcode－－>Build Settings－－>Header Search Paths里面添加/usr/include/libxml2項。
• 在Xcode－－>Build Settings－－>Other Linker Flags里面添加-lxml2項。

2.實現(xiàn)

• 拼接XML文件

//這是關(guān)于DLNA功能的DIDL-Lite標(biāo)準(zhǔn)字段值
-(void)appendXMLString
{
    //添加根節(jié)點
    GDataXMLElement * rootElement = [GDataXMLNode elementWithName:@"DIDL-Lite"];
    //根節(jié)點到屬性及值
    GDataXMLElement * rootFirstArg = [GDataXMLNode attributeWithName:@"xmlns" stringValue:@"urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/"];
    GDataXMLElement * rootSecondArg = [GDataXMLNode attributeWithName:@"xmlns:dc" stringValue:@"http://purl.org/dc/elements/1.1/"];
    GDataXMLElement * rootThirdArg = [GDataXMLNode attributeWithName:@"xmlns:upnp" stringValue:@"urn:schemas-upnp-org:metadata-1-0/upnp/"];
    GDataXMLElement * rootFourthArg = [GDataXMLNode attributeWithName:@"xmlns:dlna" stringValue:@"urn:schemas-dlna-org:metadata-1-0/"];
    [rootElement addAttribute:rootFirstArg];
    [rootElement addAttribute:rootSecondArg];
    [rootElement addAttribute:rootThirdArg];
    [rootElement addAttribute:rootFourthArg];
    
    //添加item節(jié)點
    GDataXMLElement * itemElement = [GDataXMLNode elementWithName:@"item"];
    //添加item節(jié)點的屬性及值
    GDataXMLElement * itemFirstArg = [GDataXMLNode attributeWithName:@"id" stringValue:@""];
    GDataXMLElement * itemSecondArg = [GDataXMLNode attributeWithName:@"parentID" stringValue:@"-1"];
    GDataXMLElement * itemThirdArg = [GDataXMLNode attributeWithName:@"restricted" stringValue:@"1"];//1 or ture
    [itemElement addAttribute:itemFirstArg];
    [itemElement addAttribute:itemSecondArg];
    [itemElement addAttribute:itemThirdArg];
    
    //添加title節(jié)點
    GDataXMLElement * titleElement = [GDataXMLNode elementWithName:@"dc:title"];
    //設(shè)置title的值
    [titleElement setStringValue:@"測試音頻"];
    
    //添加res節(jié)點，屬性和值
    GDataXMLElement * resElement = [GDataXMLNode elementWithName:@"res"];
    GDataXMLElement * resFisrtArg = [GDataXMLNode attributeWithName:@"duration" stringValue:@"04:48"];
    GDataXMLElement * resSecondArg = [GDataXMLNode attributeWithName:@"protocolInfo" stringValue:@"http-get:*::*"];
    [resElement setStringValue:@"www.baidu.com"];
    GDataXMLElement * upnpClassEle = [GDataXMLNode elementWithName:@"upnp:class"];
    [upnpClassEle setStringValue:@"object.item.audioItem.musicTrack"];
    
    //一層一層的往上加節(jié)點，構(gòu)成xml結(jié)構(gòu)
    [resElement addAttribute:resFisrtArg];
    [resElement addAttribute:resSecondArg];
    
    [itemElement addChild:titleElement];
    [itemElement addChild:resElement];
    [itemElement addChild:upnpClassEle];
    
    [rootElement addChild:itemElement];
    
    NSString * rootStr = [rootElement XMLString];
    NSLog(@"%@",rootStr);
    
    GDataXMLDocument * doc = [[GDataXMLDocument alloc] initWithRootElement:rootElement];
    [doc setVersion:@"1.0"];
    [doc setCharacterEncoding:@"utf-8"];
    NSString * docStr = [[NSString alloc] initWithData:doc.XMLData encoding:NSUTF8StringEncoding];
    [self saveXMLToDocDir:docStr];
}
-(void)saveXMLToDocDir:(NSString *)doc
{
    NSString * xml = [DOCDIR stringByAppendingPathComponent:@"test.xml"];
    [[NSFileManager defaultManager] createFileAtPath:xml contents:[doc dataUsingEncoding:NSUTF8StringEncoding] attributes:nil];
   
    NSLog(@"沙盒路徑：%@",xml);
}

• 解析XML文件

-(NSString *)getXMLFile
{
    NSString * filePath = [DOCDIR stringByAppendingPathComponent:@"test.xml"];
    NSString * file = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];
    return file;
}
-(void)praseXMLStringWithFile
{
    NSString * file = [self getXMLFile];
    GDataXMLDocument * doc = [[GDataXMLDocument alloc] initWithXMLString:file options:0 error:nil];
    //獲取根節(jié)點
    GDataXMLElement * rootElement = [doc rootElement];
    NSLog(@"根節(jié)點的標(biāo)簽是：%@",[rootElement name]);
    
    //獲取所有item節(jié)點
    NSArray * itemElementArray = [rootElement elementsForName:@"item"];
    
    for (int i=0; i<itemElementArray.count; i++) {
        GDataXMLElement * itemElment = itemElementArray[i];
        //獲取屬性為parentID的值
        NSString * itemFirstArg = [[itemElment attributeForName:@"parentID"] stringValue];
        NSLog(@"itemFirstArg:%@",itemFirstArg);
        
        //獲取所有title節(jié)點
        NSArray * dcTitleArray = [itemElment elementsForName:@"dc:title"];
        for (int j=0; j<dcTitleArray.count; j++) {
            GDataXMLElement * titleElement = dcTitleArray[j];
            //獲取title節(jié)點的值
            NSString * title = [titleElement stringValue];
            NSLog(@"title:%@",title);
        }
    }
}

完成。
附上DEMO。
給個贊唄～