Flutter - Dart - setState does not reload state when using with Future<> for the async function

Question

I have a Flutter code with setState() for the RaisedButton, working fine to change all the local variables like changing button color, hide/show other components on the same page etc. But when I use Future statusCode = myFun(); where myFun() is Async function, Future always returns code properly by setState() takes effect every 2nd time.

My code is here:

return RaisedButton(
    color: infBtnColor ? Colors.green : Colors.grey,
    textColor: Colors.black87,
    onPressed: () {
      setState(() {

        infBtnColor = true;    //this takes effect on click properly -always

        Future<int> statusCode = myFun(false);
        statusCode.then((value) {

          if (value == 200) {
            ESPSyncIconColor = true;   // this is to modify other icon from the AppBar
            print("Btn GREEN");
          }
          else {
            ESPSyncIconColor = false;
            print("RED");
          }
        });
      });

    }
);

And the App bar code is here:

AppBar(

    title: Text(title,style: TextStyle(fontSize:18,fontWeight: FontWeight.w300,)),
    backgroundColor: new Color(0xff303030),

    actions: <Widget>[
    Padding(
    padding: EdgeInsets.only(right: 25.0),
    child: Row(
    children: <Widget>[

    Icon(Icons.cloud_upload,size: 26,
    color: (**ESPSyncIconColor**)?Colors.green:Colors.red,

    ),],),),
    ],),

Here I am using variable ESPSyncIconColor to update Icon color from the AppBar of the same page. Which always work on second time, that too with the previous status.

Answer 1

You are calling a future inside setState. This future isn't going to complete until after setState returns and the widget is rebuilt. Instead, await or then the future and call setState afterward.

onPressed: () {
  infBtnColor = true;
  myFun(false).then((value) {
    setState(() {
      if (value == 200) {
        ESPSyncIconColor = true;   // this is to modify other icon from the AppBar
        print("Btn GREEN");
      } else {
        ESPSyncIconColor = false;
        print("RED");
      }
    });
  });
}