Login.swift

    static var username: String{
        return keychain.get("username")!
    }
    static var password: String{
        return keychain.get("password")!
    }
    
    
    func urlSession(_ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
        completionHandler(.useCredential, URLCredential(user: NetworkManager.username, password: NetworkManager.password, persistence: .synchronizable))
    }