Resposta do exercicio!

import 'package:flutter/material.dart';

class formScreen extends StatefulWidget {
  const formScreen({super.key});

  @override
  State<formScreen> createState() => _formScreenState();
}

class _formScreenState extends State<formScreen> {
  TextEditingController nameController = TextEditingController();
  TextEditingController difficultyController = TextEditingController();
  TextEditingController imageController = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        leading: const Icon(
          Icons.keyboard_return,
          size: 30,
          color: Colors.white,
        ),
        backgroundColor: Colors.blueGrey,
        title: Row(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          children: [
            const Text('Nova tarefa',
                style: TextStyle(
                    color: Colors.white, fontWeight: FontWeight.w500)),
          ],
        ),
      ),
      body: Center(
          child: Container(
            width: 375,
            height: 650,
            decoration: BoxDecoration(
                color: Colors.black12,
                borderRadius: BorderRadius.circular(10),
                border: Border.all(width: 1)),
            child: Column(
              children: [
                Padding(
                  padding: const EdgeInsets.all(8.0),
                  child: TextFormField(
                    controller: nameController,
                    decoration: InputDecoration(
                      border: OutlineInputBorder(),
                      hintText: 'Nome',
                      fillColor: Colors.white70,
                      filled: true,
                    ),
                  ),
                ),
                Padding(
                  padding: const EdgeInsets.all(8.0),
                  child: TextFormField(
                    controller: difficultyController,
                    decoration: InputDecoration(
                      border: OutlineInputBorder(),
                      hintText: 'Dificuldade',
                      fillColor: Colors.white70,
                      filled: true,
                    ),
                  ),
                ),
                Padding(
                  padding: const EdgeInsets.all(8.0),
                  child: TextFormField(
                    onChanged: (text) {
                      setState(() {

                      });
                    },
                    controller: imageController,
                    decoration: InputDecoration(
                      border: OutlineInputBorder(),
                      hintText: 'imagem',
                      fillColor: Colors.white70,
                      filled: true,
                    ),
                  ),
                ),
                Container(
                  height: 100,
                  width: 72,
                  decoration: BoxDecoration(
                    color: Colors.blue,
                    borderRadius: BorderRadius.circular(10),
                    border: Border.all(width: 1, color: Colors.blue),
                  ),
                  child: ClipRRect(
                    borderRadius: BorderRadius.circular(10),
                    child: Image.network(
                      imageController.text, fit: BoxFit.cover,
                      errorBuilder: (BuildContext context, Object exeption, StackTrace? stackTrace){
                        return Image.asset('assets/images/nophoto.jpg', fit: BoxFit.fitHeight,);
                      },),
                  ),
                ),
                ElevatedButton(
                  onPressed: () {
                    print(nameController.text);
                    print(difficultyController.text);
                    print(imageController.text);
                  },
                  child: Text('adicionar'),
                )
              ],
            ),
          )),
    );
  }
}