From my understanding, onChangeText will be called every-time the user types or remove a character in a text field which depends on the what type of functionality you need, because your app you can also detects when the editing ends on a text field and then update the state.

I've never done the in-line setters may be because I don't know what it means, but I'm sure based on the requirements of the app, we can choose different ways of managing states.