public async Task <Session> LoginAsync(string provider) { Provider = provider; try { Session session = null; switch (provider) { case Constants.FacebookProvider: session = await facebookService.LoginAsync(); break; case Constants.MicrosoftProvider: session = await microsoftService.LoginAsync(); break; case Constants.GoogleProvider: session = await googleService.LoginAsync(); break; } if (session == null) { return(null); } Save(session); return(session); } catch (Exception ex) { } return(null); }