Android c# App Login Best Practice

Question

I'm making an android App in c#, and it starts with a login page. Anytime app get closed, user has to log in again.

What's the best practice to auto-login, storing credentials somewhere and retrieving them? (if this is the best way)

Thanks

Riccardo

Ok, soon after posting this I found something about tokens and shared preference. The idea is generating a token when user log in, saving it both in server and in this shared preference thing (I will study soon!), when user opens app, there a token check between server and shared, if it's ok, login done.Right? — Raikoug, Sep 13 '16 at 02:13

score 1 · Accepted Answer · answered Sep 13 '16 at 08:43

You can follow this steps

After successful login, save credentials in SQlite db or any other database you are using.
On logout, clear these credentials using DeleteAll<>() method.
At startup/launch screen, first check if credentials are present. If yes, show user the next screen else display login screen.
If you don't wish to delete credentials, use a boolean flag in User object and mark it accordingly.
During password change, make sure to replace old credentials with new one, else user can login into the app using his/her old credentials.

score 0 · Answer 2 · answered Sep 13 '16 at 05:26

in the first you should use ISharedPreferences

using System;
using Android.App;
using Android.Content;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.OS;
using System.Collections.Generic;
using Android.Preferences;

namespace App
{
    [Activity(Label = "App", MainLauncher = true, Icon = "@drawable/icon")]
    public class MainActivity : Activity
    {

        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            // Set our view from the "main" layout resource
            SetContentView(Resource.Layout.Main);

            //to get data that already stored in Shared Preferences use prefs.get----
            //to put new data in Shared Preferences Editor use editor.put----
            ISharedPreferences prefs = PreferenceManager.GetDefaultSharedPreferences(this);
            ISharedPreferencesEditor editor = prefs.Edit();
            if (prefs.GetBoolean("is_login",false))
            {
                //prefs.GetBoolean("key",defualt value)       
                //here use is logged in alread now open main page but note 
                //you need for exmaple his id to make some opration in main page after login 
                Intent x = new Intent(this,typeof(Activity2));
                StartActivity(x);
            }
            else
            {
                //here user is not logged in now to can show login page and after that you need to put 
                //in local setting login=true like that
                editor.PutBoolean("is_login", true);
                editor.Apply();
            }
        }
    }
}

score 0 · Answer 3 · edited May 23 '17 at 11:52

Answer to this question is here in stackoverflow (after understanding sharedpreference is the best way to achieve this goal:

Here

Example with class is working very fine.

Last part of the answer (as a best practice) is WHEN checking the token, and as far as I found, is every time app contact the server, checking if token is correct or expired, or changed (due to password update or user delete).

So this best practice should be a global behavior, for example updating token when needed, and checking it when app interacts with server.

Thanks for all answers.

Android c# App Login Best Practice

3 Answers3