deserialize function error

class a{
var code:Int?
var data:String?
var message:String?
}

class b{
var id:Int?
var info:String?
}

//json:
let json="{code:1,data:{id:202,info:"...."},message:\"....\"}"

let clsa=a.deserializeFrom(json: json)
//deserialize succes,but

clsa.data="{id=\"...\"",message=\"...\'}" //debug data
//clas.data struct has been change, con't be use this string to deserialize to class b.

Start at the deserializeFrom entry point and reproduce the example using classes a and b with nested data. Inspect how the nested value is represented after deserialization, then add a regression test showing that the resulting data can be deserialized into class b and preserves the expected fields.

Written by the indexing model from the issue text.