ResponseMapperProtocol.swift

protocol ResponseMapperProtocol {
    associatedtype Item
    static func process(obj: AnyObject?) throws -> Item
}

final class SignInResponseMapper: ResponseMapper<SignInItem>, ResponseMapperProtocol {

    static func process(obj: AnyObject?) throws -> SignInItem {
        return try process(obj, parse: { json in
            let token = json["token"] as? String
            let uniqueId = json["unique_id"] as? String
            if let token = token, let uniqueId = uniqueId {
                return SignInItem(token: token, uniqueId: uniqueId)
            }
            return nil
        })
    }
}