Flutter for Beginners

Creating an Input widget

We start by creating a normal custom widget. Here, we expose some properties. Bear in mind that in a real application, we would probably expose more than the properties exposed here, but it's enough for this example:

class VerificationCodeInput extends StatefulWidget {  final BorderSide borderSide;  final onChanged;  final controller;  ... // other parts removed for brevity}

The only important property exposed here is controller. We will see the reason in a few moments. First, let's check the associated State class:

class _VerificationCodeInputState extends State<VerificationCodeInput> {    @override  Widget build(BuildContext context) {    return TextField(      controller: widget.controller,      inputFormatters: [ WhitelistingTextInputFormatter(RegExp("[0-9]")), ...