class User:Object, Mappable{

    dynamic var exId = ""
    dynamic var user = ""
    dynamic var password = ""
    dynamic var participant:Participant? = Participant()

    convenience init (exId: String, user: String, password:String, participant:Participant) {
        self.init()
        self.exId = exId
        self.user = user
        self.password = password
        self.participant = participant
    }

    required convenience init?(map: Map) {
        self.init()
    }

    // Mappable
    func mapping(map: Map) {
        exId    <- map["id"]
        user  <- map["name"]
        password <- map["password"]
        participant <- map["participantId"]
    }

}

class Participant:Object, Mappable{
    dynamic var exId = ""
    @objc dynamic var name = ""

    convenience init(exId:String, name:String) {
        self.init()
        self.exId = exId
        self.name = name
    }

    required convenience init?(map: Map) {
        self.init()
    }

    // Mappable
    func mapping(map: Map) {
        exId    <- map["id"]
        name  <- map["name"]
    }

}

{"user":{
  "id":"123456EEC",
  "name":"user",
  "pass":"1234",
  "participantId":"123EEF"}
}