简介Objective-C解析XML与JSON数据格式的方法

解析XML
本文以解析本地XML为例，网络获取到的返回值只需转换成NSData型，解析是同理

需要解析的xml文件如下，users.xml

<?xml version="1.0" encoding="UTF-8"?>
<AllUsers>
 <message>用户信息</message>
 <user>
  <name>芳仔小脚印</name>
  <age>10</age>
  <school>JiangSu University</school>
 </user>
 <user>
  <name>毒虫</name>
  <age>22</age>
  <school>NanJing University</school>
 </user>
 <user>
  <name>女神</name>
  <age>23</age>
  <school>HongKong University</school>
 </user>
</AllUsers>

我们用一个数组来存放，最终数据结构为

(
    {
    message = "用户信息";
  },
    {
    age = 10;
    name = "芳仔小脚印";
    school = "JiangSu University";
  },
    {
    age = 22;
    name = "毒虫";
    school = "NanJing University";
  },
    {
    age = 23;
    name = "女神";
    school = "HongKong University";
  }
)

解析步骤

一、声明代理 NSXMLParserDelegate

二、解析

// 遇到节点message和user时作为一个字典存放

    NSArray *keyElements = [[NSArray alloc] initWithObjects:@"message",@"user", nil];

    // 需要解析的字段

    NSArray *rootElements = [[NSArray alloc] initWithObjects:@"message",@"name",@"age",@"school", nil];

    // 获取xml文件的路径

    NSString *xmlPath = [[NSBundle mainBundle] pathForResource:@"users" ofType:@"xml"];

    // 转化为Data

    NSData *data = [[NSData alloc] initWithContentsOfFile:xmlPath];

     

    // 初始化

    NSXMLParser *xmlParser = [[NSXMLParser alloc] initWithData:data];

     

    // 代理

    xmlParser.delegate = self;

    // 开始解析

    BOOL flag = [xmlParser parse];

    if (flag) {

        NSLog(@"解析成功");

    }

    else{

        NSLog(@"解析出错");

    }

中间变量，在.m的interface的中定义

NSString *currentElement;

     

    NSString *currentValue;

     

    NSMutableDictionary *rootDic;

     

    NSMutableArray *finalArray;

代理方法

#pragma - mark 开始解析时

-(void)parserDidStartDocument:(NSXMLParser *)parser

{

    // 用数组存储每一组信息

    finalArray = [[NSMutableArray alloc] init];

     

     

}

#pragma - mark 发现节点时

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

{

    for(NSString *key in self.keyElements){

        if ([elementName isEqualToString:key]) {

            // 关键节点开始时，初始化一个字典来存放值

            rootDic = nil;

             

            rootDic = [[NSMutableDictionary alloc] initWithCapacity:0];

             

        }

        else {

            for(NSString *element in self.rootElements){

                if ([element isEqualToString:element]) {

                    currentElement = elementName;

                    currentValue = [NSString string];

                }

            }

        }

    }

     

}

#pragma - mark 发现节点值时

 

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

{

     

    if (currentElement) {

 

        currentValue = string;

        [rootDic setObject:string forKey:currentElement];

    }

     

}

#pragma - mark 结束节点时

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

{

    if (currentElement) {

        [rootDic setObject:currentValue forKey:currentElement];

        currentElement = nil;

        currentValue = nil;

    }

    for(NSString *key in self.keyElements){

 

        if ([elementName isEqualToString:key]) {

            // 关键节点结束时，将字典存放在数组中

            if (rootDic) {

 

                [finalArray addObject:rootDic];

            }

        }

    }

}

#pragma - mark 结束解析

-(void)parserDidEndDocument:(NSXMLParser *)parser

{

     

}

解析完成后，打印出finalArray为

(
 {
  message = "\U7528\U6237\U4fe1\U606f";
 },
 {
  age = 10;
  name = "\U82b3\U4ed4\U5c0f\U811a\U5370";
  school = "JiangSu University";
 },
 {
  age = 22;
  name = "\U6bd2\U866b";
  school = "NanJing University";
 },
 {
  age = 23;
  name = "\U5973\U795e";
  school = "HongKong University";
 }
)

使用SBJson拼接和解析json
1.ios解析json
使用开源json包，项目地址：
http://www.superloopy.io/json-framework/

NSData * responseData = [respones responseData]; 

      

     NSString * strResponser = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding]; 

SBJsonParser * parser = [[SBJsonParser alloc]init]; 

     NSMutableDictionary *dicMessageInfo = [parser objectWithString:strResponser]; // 解析成json解析对象 

[parser release]; 

     //发送者 

     NSString * sender = [dicMessageInfo objectForKey:@"sender"]; 

2.json嵌套对象解析：

//要上传的字符串 

    NSString *dataStr=[[NSString alloc] initWithString:@"{\"cross\":{\"1\":\"true\",\"2\":\"false\",\"3\":\"true\"}}"]; 

//获取响应返回字符串 

NSData * responseData = [respones responseData]; 

        

        NSString * strResponser = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding]; 

//嵌套解析 

SBJsonParser * parser = [[SBJsonParser alloc]init]; 

            

            NSMutableDictionary *dicMessageInfo = [parser objectWithString:strResponser]; // 解析成json解析对象 

            

            NSMutableDictionary * cross = [dicMessageInfo objectForKey:@"cross"]; 

            

            NSString *cross1= [cross objectForKey:@"1"]; 

            //解析json到各个字符串 

            //发送者 

            [parser release]; 

            NSLog(@"cross1: %@",cross1); 

3.拼接json字符串

通过使用SBJson中的SBJsonWriter类的方法- (NSString*)stringWithObject:(id)value可以将一个对象中的值格式化为json字符串，符合key/value格式的数据封装到NSDictionary后可以使用该方法进行格式化，其他数据通过拼接字符串的方式格式化。
在拼接过程中可以使用类NSMutableString的方法：

 

- (void)appendString:(NSString *)aString;、 

- (void)appendFormat:(NSString *)format, ... NS_FORMAT_FUNCTION(1,2); 

动态添加字符串。
拼接的字符串可通过json在线验证的方式验证其格式是否正确，网址为：
http://jsonlint.com/

-(NSString *) getJsonString 

{ 

    NSMutableString *json = [NSMutableString stringWithCapacity:128]; 

    NSString *jsonString=nil; 

    SBJsonWriter *writer = [[SBJsonWriter alloc] init]; 

    [json appendString:@"{\"data\":{"]; 

    [json appendFormat:@"\"%@\":\"%d\",",@"reset",reset]; 

    if(missionStatus!=NULL) 

    { 

        jsonString=[writer stringWithObject:status]; 

        if(jsonString!=NULL) 

        { 

            [json appendString:@"\"status\":"]; 

            [json appendString:jsonString]; 

        } 

    } 

    [json appendString:@"}}"]; 

    return json; 

} 

4.利用多个NSDictionary，拼接多层嵌套的json字符串，减少因手工拼接忘记加引号导致的json格式错误
示例代码：

NSDictionary *dataDictionary= [NSDictionary dictionaryWithObjectsAndKeys:mac,@"mac", 

                                   game,@"game", 

                                   devicetoken,@"devicetoken", 

                                   device,@"device", 

                                   gv,@"gv", 

                                   lang,@"lang", 

                                   os,@"os", 

                                   hardware,@"hardware", 

                                   down,@"down",nil]; 

    NSDictionary *parmDictionary= [NSDictionary dictionaryWithObjectsAndKeys:@"getSession",@"act", 

                                   dataDictionary,@"data",nil]; 

    NSDictionary *jsonDictionary=[NSDictionary dictionaryWithObjectsAndKeys:pv,@"pv", 

                                  parmDictionary,@"param",nil]; 

    SBJsonWriter *writer = [[SBJsonWriter alloc] init]; 

    

    NSString *jsonString=nil; 

    jsonString=[writer stringWithObject:jsonDictionary]; 

    NSLog(@"%@",jsonString);