How can I migrate in AFNetworking 3.0?

I am migrating in AFNetworking 3.0. I am using AFHTTPRequestOperation in AFNetworking but it was removed in recent updates. I tried all the possible solution. Basically I need to post a JSON with Header. I convert my NSDIctionary into a JSON object then add it as string. Here is the sample JSON with Header of mine

RequestHeader={
  "lname" : "sadhsdf",
  "bday" : "2003-03-13",
  "age" : "12",
  "address" : "dsfhskdjgds",
  "gender" : "M",
  "cnumber" : "12312412",
  "fname" : "sadhsdf",
  "RequestType" : "userregistration",
  "Email" : "sldjlkasd@sjdhflksdf.com",
  "status" : "dsfhskdjgds",
  "Password" : "123456"
}

RequestHeader is an NSString and the rest are NSDictionary.

How can I apply it in AFNetworking 3.0? Thank you in advance.