....
      body: StreamBuilder(
        stream: _movieCollection.snapshots(),
        builder: (context, snapshot) {
          switch (snapshot.connectionState) {
            case ConnectionState.waiting:
              return Center(child: CircularProgressIndicator());
            default:
              return ListView.builder(
                itemCount: snapshot.data.documents.length,
                itemBuilder: (context, index) {
                  return _mainContent(snapshot.data.documents[index]);
                },
              );
          }
        },
      ),
....