iOS 自带的解析json的类

数据源是NSData类型的，也可以是NSString类型的，但是NSString类型的可以转换为NSData类型的.

     NSString *responseString;

     NSData *data = [responseString dataUsingEncoding:NSUTF8StringEncoding];

     NSError *error = nil;

     id jsonObject = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:&error];

     if ([jsonObject isKindOfClass:[NSDictionary class]])

     {

          NSDictionary *dictionary = (NSDictionary *)jsonObject;

          NSLog(@"Dersialized JSON Dictionary = %@", deserializedDictionary);

     }

     else if ([jsonObject isKindOfClass:[NSArray class]])

     {

          NSArray *nsArray = (NSArray *)jsonObject;

          NSLog(@"Dersialized JSON Array = %@", deserializedArray);

     } 

     else 

     {

          NSLog(@"An error happened while deserializing the JSON data.");

     }