التعامل مع FutureBuilder في flutter

تحيه طيبه للجميع

لدي استفسار لو تكرمتم 

لماذا list view  لدى استعمالها مع Future Builder تعمل بدون ان اضع الدالة في initState()؟

وهل يوجد حل حتى اجعلها تعمل فقط لو قمت بوضعها في initState()؟

مثل الصفحة التالية:

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {


  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {





  @override
  void initState() {


    super.initState();
  }

  bool showicon=false;
  var apiURL;
  Future getdataCat() async {
    setState(() {
      showicon=true;
    });
    apiURL = '***********************';
    var response = await http.post(Uri.parse(apiURL));
    var responsebody = jsonDecode(response.body);
    if (responsebody.length >0){
      return responsebody;
    }else{
      showicon=false;

    }
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Flexible(
              child: FutureBuilder(
                future: getdataCat(),
                builder: (context, AsyncSnapshot snapshot) {
                  if (!snapshot.hasData) {
                    // still waiting for data to come
                    return showicon
                        ? Center(
                        child: CircularProgressIndicator(
                          color: Colors.black,

                        ))
                        : SizedBox(
                        height: MediaQuery.of(context).size.height / 1.3,
                        child: Center(
                            child: Image.asset(
                              'assets/data.png',
                              fit: BoxFit.contain,
                              width: 180,
                              height: 180,
                            )));
                  } else if (snapshot.hasData &&
                      snapshot.data.isEmpty &&
                      snapshot.data <= 0) {
                    // got data from snapshot but it is empty

                    return SizedBox(
                        height: MediaQuery.of(context).size.height / 1.3,
                        child: Center(
                            child: Image.asset(
                              'assets/data.png',
                              fit: BoxFit.contain,
                              width: 180,
                              height: 180,
                            )));
                  } else {
                    // got data and it is not empty
                    return

                      GridView.builder(
                        physics: ScrollPhysics(),
                        gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
                            crossAxisCount: 2,
                            childAspectRatio: 3.4),
                        itemCount: snapshot.data.length,
                        itemBuilder: (context, index) {
                          return Container(
                            child: Card(
                              child: Column(
                                crossAxisAlignment:
                                CrossAxisAlignment.stretch,
                                children: <Widget>[
                                  Flexible(
                                      child: GestureDetector(
                                        child: Column(
                                            crossAxisAlignment:
                                            CrossAxisAlignment.stretch,
                                            children: <Widget>[
                                              Flexible(
                                                child: CachedNetworkImage(
                                                  imageUrl:
                                                  "${snapshot
                                                      .data[index]['image']}",
                                                  height: 180,
                                                  fit: BoxFit.cover,
                                                  errorWidget:
                                                      (context, url, error) =>
                                                      Icon(Icons.error),
                                                ),
                                              ),
                                              Center(
                                                child: Text(
                                                    "${snapshot
                                                        .data[index]['name']}"
                                                )
                                              )
                                            ]),
                                     
                                       
                                      )),
                                ],
                              ),
                            ),
                          );
                              
                        },
                      );

                  }
                },
              ),
            )

          ],
        ),
      ),

    );
  }
}