Qfyilyi

I looked at the FirebaseUI sign-in methods. on the first page of the explanation there is a "Sign in with a pre-built UI" as shown here: Easily add sign-in to your Android app with FirebaseUI. This page contains the following code:

// Choose authentication providers

List<AuthUI.IdpConfig> providers = Arrays.asList(

        new AuthUI.IdpConfig.EmailBuilder().build(),

        new AuthUI.IdpConfig.PhoneBuilder().build(),

        new AuthUI.IdpConfig.GoogleBuilder().build(),

        new AuthUI.IdpConfig.FacebookBuilder().build(),

        new AuthUI.IdpConfig.TwitterBuilder().build());



// Create and launch sign-in intent

startActivityForResult(

        AuthUI.getInstance()

                .createSignInIntentBuilder()

                .setAvailableProviders(providers)

                .build(),

        RC_SIGN_IN);

And then

@Override

protected void onActivityResult(int requestCode, int resultCode, Intent data) {

    super.onActivityResult(requestCode, resultCode, data);



    if (requestCode == RC_SIGN_IN) {

        IdpResponse response = IdpResponse.fromResultIntent(data);



        if (resultCode == RESULT_OK) {

            // Successfully signed in

            FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();

            // ...

        } else {

            // Sign in failed. If response is null the user canceled the

            // sign-in flow using the back button. Otherwise check

            // response.getError().getErrorCode() and handle the error.

            // ...

        }

    }

}

But, when I look at their example of the how to authenticate with phone via SMS, this code is no where to be seen, yet the verification works.
The phone authentication code can be seen in their snippet:
PhoneAuthActivity.java

So when do I need to use this code and when not? What is the purpose of this part?

There are two main ways to implement Firebase Authentication:

1. Use the so-called headless API and build your own API and flows on top of that.


2. Use FirebaseUI, which is a UI library that (in this case) encapsulates the Firebase Authentication sign-in flow. It calls the Firebase Authentication API under the hood, as you can see in its open source implementation.

The first snippet you showed configures FirebaseUI, specifically saying what providers (Google, Facebook, Email+Password, Phone, Twitter) are enabled and then starting an activity to kick off the flow.

The second snippet uses the Firebase Authentication API directly to implement a part of the authentication flow.

If you're using FirebaseUI, follow the documentation for configuring phone number auth in its repo. As far as I can see there, this doesn't require the onActivityResult you shared. Most likely that flow is already encapsulated in FirebaseUI itself.