flutter在使用showModalBottomSheet时，当弹层上有Textfield时，会出现键盘遮挡问题，解决办法如下：

showModalBottomSheet(
          backgroundColor: Colors.white,
          isScrollControlled: true,
          context: context,     
          builder: (ctx) {
            return Container(
        height: 350,
        margin: EdgeInsets.only(bottom:MediaQuery.of(context).viewInsets.bottom),//主要是这句
            );
          });

有兴趣的可以看下MediaQuery.of(context).viewInsets的解释

  /// The parts of the display that are completely obscured by system UI,
  /// typically by the device's keyboard.
  ///
  /// When a mobile device's keyboard is visible `viewInsets.bottom`
  /// corresponds to the top of the keyboard.
  ///
  /// This value is independent of the [padding] and [viewPadding]. viewPadding
  /// is measured from the edges of the [MediaQuery] widget's bounds. Padding is
  /// calculated based on the viewPadding and viewInsets. The bounds of the top
  /// level MediaQuery created by [WidgetsApp] are the same as the window
  /// (often the mobile device screen) that contains the app.
  ///
  /// See also:
  ///
  ///  * [ui.window], which provides some additional detail about this property
  ///    and how it relates to [padding] and [viewPadding].
  final EdgeInsets viewInsets;