login.cs

IEnumerator Login()
{
    if (loginStarted)
    {
        loginDone = true;
        loginFailed = true;
        Debug.Log("Multiple calls to login detected. Rejected attempt.");
    }
    else
    {

        loginStarted = true;
        Debug.Log("Login called");

        // Set up the information for the auth request.
        LoginPayload payload = new LoginPayload();
        payload.game_key = this.LootLockerAPIKey;
        payload.player_identifier = this.PlayerIdentifier;
        payload.platform = "steam";
        payload.game_version = "0.0.1";

        String requestBody = payload.ToJSON();

        Debug.Log(requestBody);

        using (UnityWebRequest webRequest = UnityWebRequest.Post(LootLocker.baseUrl + "v2/session", ""))
        {
            // Create an upload handler and turn the string into a byte array
            UploadHandler uploader = new UploadHandlerRaw(Encoding.ASCII.GetBytes(requestBody));
            webRequest.uploadHandler = uploader;

            // Set header to let the server know we are sending JSON
            webRequest.SetRequestHeader("Content-Type", "application/json");

            // Send request and wait for the response
            yield return webRequest.SendWebRequest();

            if (webRequest.isNetworkError || webRequest.isHttpError)
            {
                Debug.Log("Login failed!");
                Debug.Log(webRequest.error);
                Debug.Log(webRequest.downloadHandler.text);

                // Login failed, make sure to break the while loop in Start()
                this.loginFailed = true;
                this.loginDone = true;
            }
            else
            {
                Debug.Log("Login succeeded!");
                Debug.Log(webRequest.responseCode);
                Debug.Log(webRequest.downloadHandler.text);

                // Login succeeded! Parse the response so we can use the data returned
                PlayerInfoResponse pir = PlayerInfoResponse.ParseSuccessfulLoginResponse(webRequest.downloadHandler.text);

                Debug.Log(pir.player_id);
                Debug.Log(pir.session_token);

                // Mark login as done and save the request token
                this.loginDone = true;
                this.sessionToken = pir.session_token.ToString();
            }
        }
        Debug.Log("Login completed");
    }
}

[System.Serializable]
public class PlayerInfoResponse
{
    public string request_token;
    public bool success;
    public bool seen_before;
    public int player_id;
    public bool check_grant_notifications;
    public bool check_deactivation_notifications;

    public static PlayerInfoResponse ParseSuccessfulLoginResponse(string jsonString)
    {
        return JsonUtility.FromJson<PlayerInfoResponse>(jsonString);
    }
}

[System.Serializable]
public class LoginPayload
{
    public string game_key;
    public string player_identifier;
    public string game_version;
    public string platform;

    public string ToJSON()
    {
        return JsonUtility.ToJson(this);
    }
}