Rebirth's request model (reference to APIKit)

protocol XMLDecodable{}
protocol JSONDecodable{
    associatedtype DecodedType = Self
}

protocol RequestType{
    associatedtype ResponseType
    
    var root: String{ get }
    var endpoint: String{ get }
    var method: String{ get }
    var timeoutInterval: Int{ get }
    
    func header() -> [String: String]
    func parameter() -> [String: AnyObject]
}

extension RequestType where ResponseType: XMLDecodable{
    var timeoutInterval: Int{
        return 10
    }
    
    func header() -> [String: String]{
        return ["Content-Type": "application/x-www-form-urlencoded"]
    }
    
    func responseFromXml() -> String{
        API.sendRequest(self){print($0)}
        return "xml"
    }
}

extension RequestType where ResponseType: JSONDecodable, ResponseType.DecodedType == ResponseType{
    var timeoutInterval: Int{
        return 5
    }
    
    func header() -> [String: String]{
        return ["Content-Type": "application/json"]
    }
    
    func responseFromJson() -> String{
        API.sendRequest(self){print($0)}
        return "json"
    }
}

struct XMLResponse: XMLDecodable{}

struct JSONResponse: JSONDecodable{}

struct API {
    static func sendRequest<T: RequestType>(request: T, completion: (T.ResponseType -> Void)?){
    }
}

struct JSONRequest: RequestType{
    typealias ResponseType = JSONResponse
    
    let root = ""
    let endpoint = ""
    let method = "GET"
    
    func parameter() -> [String : AnyObject] {
        return [:]
    }
}

struct XMLRequest: RequestType{
    typealias ResponseType = XMLResponse
    
    let root = ""
    let endpoint = ""
    let method = "GET"
    
    func parameter() -> [String : AnyObject] {
        return [:]
    }
}

let jsonRequest = JSONRequest()
jsonRequest.header() // -> ["Content-Type": "application/json"]
jsonRequest.responseFromJson() // -> "json"
print(jsonRequest.timeoutInterval) // -> 5

let xmlRequest = XMLRequest()
xmlRequest.header() // -> ["Content-Type": "application/x-www-form-urlencoded"]
xmlRequest.responseFromXml() // -> "xml"
print(xmlRequest.timeoutInterval) // -> 10