title: create an instance of Bloc by BlocProvider in initState in flutter
body: <p>is it a good practice to initialize and create instance of Bloc in InItState() method in statefulWidget? or not, and why, thank you:</p>
  <pre><code>LoginBloc loginBloc;
  
    @override
    void initState() {
      loginBloc = BlocProvider.of&lt;LoginBloc&gt;(context);
      super.initState();
    }
  </code></pre>