Xamarin Firebase PhoneAuth for Xamarin Forms

Question

I need to create a Xamarin Forms app that has Firebase Phone Auth. There is a package for Xamarin Firebase Authentication, with phone authentication, but there is no documentation for Xamarin Forms.

So far, for Android, I have:

public class FirebaseAuthenticator : IFirebaseAuthenticator
    {
        public async Task<string> RegisterWithPhoneNumber(string number)
        {
            PhoneAuthCallbacks phoneAuthCallbacks = new PhoneAuthCallbacks();
            var user = await PhoneAuthProvider.Instance.VerifyPhoneNumber(number, 60, TimeUnit.Seconds, this, phoneAuthCallbacks);
            return user;
        }
    }

My PhoneAuthCallbacks class:

public class PhoneAuthCallbacks : PhoneAuthProvider.OnVerificationStateChangedCallbacks
    {
        public override void OnVerificationCompleted(PhoneAuthCredential credential)
        {
            // This callback will be invoked in two situations:
            // 1 - Instant verification. In some cases the phone number can be instantly
            //     verified without needing to send or enter a verification code.
            // 2 - Auto-retrieval. On some devices Google Play services can automatically
            //     detect the incoming verification SMS and perform verification without
            //     user action.        
            FirebaseAuth.Instance.SignInWithCredential(credential);
            System.Diagnostics.Debug.WriteLine("onVerificationCompleted");
        }

        public override void OnVerificationFailed(FirebaseException exception)
        {
            // This callback is invoked in an invalid request for verification is made,
            // for instance if the the phone number format is not valid.
            System.Diagnostics.Debug.WriteLine("onVerificationFailed: " + exception);
        }

        public override void OnCodeSent(string verificationId, PhoneAuthProvider.ForceResendingToken forceResendingToken)
        {
            // The SMS verification code has been sent to the provided phone number, we
            // now need to ask the user to enter the code and then construct a credential
            // by combining the code with a verification ID.
            base.OnCodeSent(verificationId, forceResendingToken);
            System.Diagnostics.Debug.WriteLine("onCodeSent" + verificationId);
        }
    }

But it doesn't work. In RegisterWithPhoneNumber, 'this' gives an error "Cannot convert from xx.Droid.FirebaseAuthenticator to Android.App.Activity"

Raja Indirajith Raja Indirajith · Accepted Answer · 2019-04-14T08:07:26

Since your FirebaseAuthenticator is not inherent from Activity, you cannot use this in the call function. You can hold the Main Activity as a static variable and use in the dependency services. Added the code below

public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
{
    internal static Activity CurrentActivityRef { get; private set; }

    protected override void OnCreate(Bundle savedInstanceState)
    {
        TabLayoutResource = Resource.Layout.Tabbar;
        ToolbarResource = Resource.Layout.Toolbar;

        base.OnCreate(savedInstanceState);

        Xamarin.Essentials.Platform.Init(this, savedInstanceState);
        global::Xamarin.Forms.Forms.Init(this, savedInstanceState);

        var fapp = FirebaseApp.InitializeApp(this);

        LoadApplication(new App());
        CurrentActivityRef = this;

    }

}

and in your Dependency Service Implementation

public class FirebaseAuthenticator: IFirebaseAuthenticator
{

    public void RegisterOrLoginWithMobileNumber(string MobileNumber)
    {

        Activity activity = MainActivity.CurrentActivityRef;
        PhoneAuthCredentialCallBack callBack = new PhoneAuthCredentialCallBack();
        PhoneAuthProvider.Instance.VerifyPhoneNumber(MobileNumber,
                                                                  60,
                                                                  TimeUnit.Seconds,
                                                                  activity, callBack
                                                                  );

    }
}

Xamarin Firebase PhoneAuth for Xamarin Forms

1 Answers