title: Flutter Firebase Phone auth reCaptcha duplicate my login page after verification on iOS
body: <p>I have a login page with juste one field for phone number and im using Firebase Phone Auth.
  Everything is okay except when google reCaptcha appeared in the web browser (not google chrome and not Safari, just a web view), after verification, the web browser have to back to my login page but at this time, i see another login page (initState called) above my login page.</p>
  <p>Is there anyway to detect at least when reCaptcha finished its job ?</p>
  <p>Login function code:</p>
  <pre><code>Future login(String mobile) async
  {
      setState((){loginInProcess=true;sent=null;});
      this.phoneNumber = mobile;
      FirebaseAuth _auth = FirebaseAuth.instance;
      _auth.setSettings(appVerificationDisabledForTesting:false);
      _auth.verifyPhoneNumber(
           phoneNumber: this.phoneNumber,
           timeout: this.expiredCode,
           verificationCompleted: _verificationCompleted,
           verificationFailed: verificationFailed,
           codeSent: codeSent,
           codeAutoRetrievalTimeout: codeAutoRetrievalTimeout
      ).catchError((error){
           setState((){loginInProcess=false;sent=false;});
      });
  }
  </code></pre>