Basic Questions regarding UI and business logic separation

[haaris94]

I have the following questions

1. Is it ok to initialize Controllers inside the build method of the Stateless widget, is it bad for performance?
2. If I initialize the controllers outside the build method, it gives me an error 'controller is initialized with non-nullable variable'.
3. If I want to update the value of the TextField using TextEditingController from the Controller class, most tutorial advice to create the TextEditingController in the Controller class, isn't it bad to bring UI code to the Controller class. is it good practice?
4. Is there any way to trigger a method like showSnackbar() in View class(Stateless Widget) from the Controller when the value of the msg.obs changes in the Controller class

Thank you. I am new to this package.

[ashunasar]

can you please share the code