initStatus method
this method will be called only once in state's lifecircle,immediately called after initState
recommend to init your resources in this method rather than initState
Implementations of this method should start with a call to the inherited method
Implementation
@override
void initStatus() {
super.initStatus();
textEditingController = TextEditingController(
text: value == null ? '' : widget.displayStringForOption(value!));
}