Flutter No Material widget found报错的解决办法

    我爱模板网利用showCupertinoModalPopup做了一个类似于js中的prompt效果的弹窗，里面有TextField，热更新时，提示下面的错误：
I/flutter (25517): No Material widget found.
I/flutter (25517): TextField widgets require a Material widget ancestor.
I/flutter (25517): In material design, most widgets are conceptually "printed" on a sheet of material. In Flutter's
I/flutter (25517): material library, that material is represented by the Material widget. It is the Material widget
I/flutter (25517): that renders ink splashes, for instance. Because of this, many material library widgets require that
I/flutter (25517): there be a Material widget in the tree above them.
I/flutter (25517): To introduce a Material widget, you can either directly include one, or use a widget that contains
I/flutter (25517): Material itself, such as a Card, Dialog, Drawer, or Scaffold.
I/flutter (25517): The specific widget that could not find a Material ancestor was:

    重点是：“No Material widget found.”和“TextField widgets require a Material widget ancestor.”，显而易见，TextField 必须包含在 Material 里面。而showDialog和showCupertinoModalPopup都在 Material 节点之外，除了 TextField，还有下面
AppBar
BottomAppBar
FloatingActionButton
Drawer
SnackBar
BottomSheet
BottomNavigationBar
ListTile
等等
    都使用了Material 风格的widget ，都需要Scaffold作为根布局，所以，将弹窗的widget外面套个Scaffold即可，如下：

return Scaffold(
    backgroundColor: Color.fromRGBO(0, 0, 0, 0),  //这个有必要设置下，因为Scaffold默认有不透明背景，影响弹窗显示，这里把背景设置为透明。
    body://这里放刚才的widget，就没问题了。
);