我不能使用弯曲导航栏在Flutter，当我滑动屏幕，所以弯曲导航栏的按钮也在移动，但当我点击弯曲导航栏的按钮什么也没有发生.我认为**onTap（）**没有正常工作。当我点击按钮时如何导航页面？这是我的程序代码=>

static final String id = 'profile_page';
  @override
  _PagesState createState() => _PagesState();
}

class _PagesState extends State<Pages> {
  PageController _pageController;

  int _Page=0;

  @override
  void initState() {
    super.initState();
    _pageController = PageController();
  }

  @override

  Widget build(BuildContext context) {
    return Scaffold(

        body: PageView(

            controller: _pageController,
          children: <Widget>[

            Search(),
            Trending(),
            Friends(),
            Profile(),
          ],
          onPageChanged: (int index) {
            setState(() {

              _pageController.jumpToPage(index);
            });
          }
          ),

          bottomNavigationBar: CurvedNavigationBar(
            animationCurve: Curves.easeInOutBack,

            index:3,

            items: <Widget>[
              Icon(Icons.search, size: 30, color: Colors.white, ),
              Icon(Icons.trending_up, size: 30, color: Colors.white),
              Icon(Icons.group, size: 30, color: Colors.white),
              Icon(Icons.person, size: 30, color: Colors.white)
            ],
            color: Colors.blueAccent,
            backgroundColor: Colors.white,
            height: 60.0,
            onTap: (int index) {
             setState(() {
               _pageController.jumpToPage(index);
             });
            },

          ),
        );

  }
}