Facebook authentication without login button

Question

I have followed some Facebook API 3.0 tutorials, including the Login/Logout and the Publish To Feed examples. So the login works this way:

1. App opens, shows a fragment which displays a login button
2. User clicks login, the authentication is done via the referenced FacebookSDK library (com.facebook.widget.LoginActivity) and the provided code using sessions.
3. User is redirected to next screen

I don't want to make the user to login this way. I want them to use my app without any login/registration, then if they click on a facebook specific feature e.g. share a note on Facebook, then the app should ask them whether they let Facebook use their app or something, you know the usual stuff. Without this I get a nullpointer in the publishFeedDialog() function as session is null, because no login has been made.

So my question is, how can I ignore the SplashFragment with the Login button, so when the user clicks on a Facebook feature in my app, no new screen is displayed with a login button, but only the default Facebook authentication window that users are used to?

Answer 1

@erdomester, @sromku

Facebook launch new sdk version 4.x where Session is deprecated,

There new concept of login as from facebook

LoginManager and AccessToken - These new classes perform Facebook Login

So, Now you can access Facebook authentication without login button as

layout.xml

    <Button             android:id="@+id/btn_fb_login"             .../> 

MainActivity.java

private CallbackManager mCallbackManager;  @Override public void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);      FacebookSdk.sdkInitialize(this.getApplicationContext());      mCallbackManager = CallbackManager.Factory.create();      LoginManager.getInstance().registerCallback(mCallbackManager,             new FacebookCallback<LoginResult>() {                 @Override                 public void onSuccess(LoginResult loginResult) {                     Log.d("Success", "Login");                  }                  @Override                 public void onCancel() {                     Toast.makeText(MainActivity.this, "Login Cancel", Toast.LENGTH_LONG).show();                 }                  @Override                 public void onError(FacebookException exception) {                     Toast.makeText(MainActivity.this, exception.getMessage(), Toast.LENGTH_LONG).show();                 }             });      setContentView(R.layout.activity_main);      Button btn_fb_login = (Button)findViewById(R.id.btn_fb_login);      btn_fb_login.setOnClickListener(new View.OnClickListener() {         @Override         public void onClick(View view) {               LoginManager.getInstance().logInWithReadPermissions(this, Arrays.asList("public_profile", "user_friends"));         }     });  } 

Edit

If you don't add the following, it won't work (rightly pointed out by @Daniel Zolnai in comment below):

@Override protected void onActivityResult(int requestCode, int resultCode, Intent data) {     super.onActivityResult(requestCode, resultCode, data);     if(mCallbackManager.onActivityResult(requestCode, resultCode, data)) {         return;     } }