Future Builder

FutureBuilder<List>(
                      future: GetSchedule().getService(),
                      builder:
                          (BuildContext context, AsyncSnapshot<List> snapshot) {
                        switch (snapshot.connectionState) {
                          case ConnectionState.active:
                          case ConnectionState.none:
                          case ConnectionState.waiting:
                            return Center(
                              child: Padding(
                                padding:
                                    EdgeInsets.only(top: 16.0, bottom: 16.0),
                                child: CircularProgressIndicator(),
                              ),
                            );
                            break;
                          case ConnectionState.done:
                            if (!snapshot.hasData) {
                              return SizedBox(
                                height: 80,
                                child: Container(
                                  padding:
                                      EdgeInsets.only(top: 8.0, bottom: 8.0),
                                  child: Center(
                                    child: Text(
                                      "Sem serviços disponiveis no momento!",
                                      style: TextStyle(
                                          fontWeight: FontWeight.w200),
                                    ),
                                  ),
                                ),
                              );
                            } else {
                              return ListView.builder(
                                shrinkWrap: true,
                                itemCount: snapshot.data.length,
                                itemBuilder: (context, index) {
                                  return ListTile(
                                    onTap: () {
                                      setState(() {
                                        service = true;
                                        _service = snapshot.data[index]["id"];
                                        Navigator.of(context).pop();
                                      });
                                    },
                                    leading: CircleAvatar(
                                      radius: 25.0,
                                      backgroundColor: Colors.yellow,
                                      backgroundImage: NetworkImage(snapshot
                                          .data[index]["image"]),
                                    ),
                                    title: Text(
                                      snapshot
                                          .data[index]["name"],
                                      style: TextStyle(
                                          fontWeight: FontWeight.w300),
                                    ),
                                    trailing: Column(
                                      children: <Widget>[
                                        Text(
                                          "R\$${snapshot.data[index]["price"]}",
                                          style: TextStyle(
                                              fontWeight: FontWeight.w300),
                                        ),
                                        Text(
                                            "${snapshot.data[index]["time"]} min")
                                      ],
                                    ),
                                  );
                                },
                              );
                            }
                        }
                      },
                    ),