sign up with phone number firebase flutter code example

Example: flutter firebase using phone auth

class LoginScreen extends StatelessWidget {  final _phoneController = TextEditingController();  final _passController = TextEditingController();  //Place A  @override  Widget build(BuildContext context) {    return Scaffold(        body: Container(          padding: EdgeInsets.all(32),          child: Form(            child: Column(              crossAxisAlignment: CrossAxisAlignment.start,              mainAxisAlignment: MainAxisAlignment.center,              children: <Widget>[                Text("Login", style: TextStyle(color: Colors.lightBlue, fontSize: 36, fontWeight: FontWeight.w500),),                SizedBox(height: 16,),                TextFormField(                  decoration: InputDecoration(                      enabledBorder: OutlineInputBorder(                          borderRadius: BorderRadius.all(Radius.circular(8)),                          borderSide: BorderSide(color: Colors.grey[200])                      ),                      focusedBorder: OutlineInputBorder(                          borderRadius: BorderRadius.all(Radius.circular(8)),                          borderSide: BorderSide(color: Colors.grey[300])                      ),                      filled: true,                      fillColor: Colors.grey[100],                      hintText: "Phone Number"                  ),                  controller: _phoneController,                ),                SizedBox(height: 16,),                TextFormField(                  decoration: InputDecoration(                      enabledBorder: OutlineInputBorder(                          borderRadius: BorderRadius.all(Radius.circular(8)),                          borderSide: BorderSide(color: Colors.grey[200])                      ),                      focusedBorder: OutlineInputBorder(                          borderRadius: BorderRadius.all(Radius.circular(8)),                          borderSide: BorderSide(color: Colors.grey[300])                      ),                      filled: true,                      fillColor: Colors.grey[100],                      hintText: "Password"                  ),                  controller: _passController,                ),                SizedBox(height: 16,),                Container(                  width: double.infinity,                  child: FlatButton(                    child: Text("Login"),                    textColor: Colors.white,                    padding: EdgeInsets.all(16),                    onPressed: (){                        //code for sign in                        Place B                    },                    color: Colors.blue,                  ),                )              ],            ),          ),        )    );  }}