private async void SignIn()
        {
            var proxy = new AccountProxy();

            var signInResponse = await proxy.SignIn(model.Email, model.Password);

            if (signInResponse.Succeeded)
            {
                Credentials.Instance.SignIn(signInResponse.Response);

                var roleResponse = await proxy.GetRole();

                var role = (RoleType)roleResponse.Response.Value <int>("role");

                var profileResponse = await proxy.GetProfile();

                var navParams = new NavigationParameters();

                switch (role)
                {
                case RoleType.Buyer:
                    var buyerModel = profileResponse.Response.Value <JToken>("response").ToObject <BuyerProfileModel>();
                    navParams.Add("model", buyerModel);
                    await navigationService.NavigateAsync("/Navigation/BuyerMode/BuyerProfile", navParams);

                    break;

                case RoleType.Seller:
                    var sellerModel = profileResponse.Response.Value <JToken>("response").ToObject <SellerProfileModel>();
                    sellerModel.StarUrl = "ic_rating_star";
                    navParams.Add("model", sellerModel);
                    await navigationService.NavigateAsync("/Navigation/SellerMode/SellerProfile", navParams);

                    break;
                }
            }
        }