how to distribute space between multiple items

Question

I am trying to add an image that covers the top 20% of the screen and the other 80% should be a grid of cards. The image needs to be in the body and not on the Appbar. I made the grid of cards, and then I tried to put the image and the grid in a column. The implementation is the following.

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        primary: true,
        appBar: AppBar(
        elevation: 4.0,
        backgroundColor: Color(0xfff8f8f8),
        title: Center(child: titleLogo,),
        ),
  //------------ PROBLEM BELOW ----------------
        body: new Column(
          children: <Widget>[
            titleLogo,   //Image object
            TheGridView().build()  //Returns a GridView object
            ],
      ),
  ),
);

}

I am getting the following error

I/flutter (21751): The following assertion was thrown during performResize():
I/flutter (21751): Vertical viewport was given unbounded height.
I/flutter (21751): Viewports expand in the scrolling direction to fill their container.In this case, a vertical
I/flutter (21751): viewport was given an unlimited amount of vertical space in which to expand. This situation
I/flutter (21751): typically happens when a scrollable widget is nested inside another scrollable widget.
I/flutter (21751): If this widget is always nested in a scrollable widget there is no need to use a viewport because
I/flutter (21751): there will always be enough vertical space for the children. In this case, consider using a Column
I/flutter (21751): instead. Otherwise, consider using the "shrinkWrap" property (or a ShrinkWrappingViewport) to size
I/flutter (21751): the height of the viewport to the sum of the heights of its children.

Any suggestion is highly appreciated. Thank you in advance.

Answer 1

for distributing space between multiple items you should use the Expanded widget like this:

return new Column(
  children: <Widget>[
    new Expanded(
      flex: 2,
      child: new Container(
        color: Colors.red,
      ),
    ),
    new Expanded(
      flex: 8,
      child: new Container(//use your Gridview instead 
        color: Colors.green,
      )
    )
  ],

);