How to refresh an AlertDialog in Flutter?

Question

Currently, I have an AlertDialog with an IconButton. The user can click on the IconButton, I have two colors for each click. The problem is that I

Answer 1

Currently to retrieve the value of Dialog I use

showDialog().then((val){
setState (() {}); 
print (val);
});

Example 1st screen

    onPressed: () { 
    showDialog(
       context: context,
       barrierDismissible: false,
       builder: (context) {
         return AddDespesa();
       }).then((val) {
         setState(() {});
         print(val);
        }
    );
   }

2nd screen

AlertDialog(
    title: Text("Sucesso!"),
    content: Text("Gasto resgristrado com sucesso"),
    actions: [
    FlatButton(
      child: Text("OK"),
      onPressed: () {
         Navigator.pop(context, true);
      },
     ),
   ],
 );

Will be printed true,