1、从https://github.com/stig/json-framework/中下载json框架：json-framework

2、解压下载的包，将class文件夹下的所有文件导入到当前工程下。

3、在使用的文件中加入导入语句 ：#import "SBJson.h"

4、将json字符串转为NSDictionary对象。

       

NSString *temp=@"{\"中国\":{
                          \"北京\":{\"北京1\":1,\"北京2\":2,\"北京3\":3},
                         \"上海\":{\"上海1\":4,\"上海2\":5,\"上海3\":6},
                         \"广州\":{\"广州1\":7,\"广州2\":8,\"广州3\":9}}}";
NSDictionary *items = [temp JSONValue];

NSString *temp=@"{\"中国\":{                           \"北京\":{\"北京1\":1,\"北京2\":2,\"北京3\":3},                          \"上海\":{\"上海1\":4,\"上海2\":5,\"上海3\":6},                          \"广州\":{\"广州1\":7,\"广州2\":8,\"广州3\":9}}}"; NSDictionary *items = [temp JSONValue];

 5、递归遍历解析出的NSDictionary对象

 

-(void)visitDict:(NSDictionary *)dict{
  NSArray *keys=[dict allKeys];
  for (NSString *key in keys) {
     NSString *result=[NSString stringWithFormat:@"key=%@,value=%@",key,[dict objectForKey:key]];
     NSLog(result);
     if([[dict objectForKey:key] isKindOfClass:[NSDictionary class]]){
            [self visitDict:[dict objectForKey:key]];
     }
   }
}

-(void)visitDict:(NSDictionary *)dict{  NSArray *keys=[dict allKeys];  for (NSString *key in keys) {     NSString *result=[NSString stringWithFormat:@"key=%@,value=%@",key,[dict objectForKey:key]];     NSLog(result);     if([[dict objectForKey:key] isKindOfClass:[NSDictionary class]]){            [self visitDict:[dict objectForKey:key]];     }   }}

 6、将解析出的NSDictionary对象还原为json字符串

                

NSString * jsonStr=[items JSONRepresentation];

NSString * jsonStr=[items JSONRepresentation];