Swift如何在NSMutable数组中添加键值

Question

我有一个nsmutable数组，如何在索引号

的nsmutable数组中添加一个keyvalue

这是数组

 (
           {
           id = 1;
           name = "Tommy";
       },
           {
           id = 2;
           name = "Dad";
       },
           {
           id = 3;
           name = "Mom";
       },
           {
           id = 4;
           name = "Vic";
       },
           {
           id = 5;
           name = "Tom";
       },
           {
           id = 6;
           name = "Pam";
       }
   )

现在索引编号3如何添加＆＃34; Class = 4th＆＃34;并更改名称

 {
               id = 4;
               name = "Nishant ";
               class = "4th"
           }

请给我ME解决方案 我是斯威夫特的新人。