space between items in gridview flutter - flutter

Question

I have a gridview with 6 items (cards with images and text). I want those 6 items to fit me on the screen but the gridview leaves all the space I can between items by jumping 2 items off the screen.
I leave a picture of what I want and what I have.
Thank you.
return MaterialApp(
home: Scaffold(
body: Container(
margin: EdgeInsets.only(top: 0),
child: Stack(
alignment: AlignmentDirectional.topCenter,
children: <Widget>[
Container(
height: 200,
color: Colors.black,
),
Container(
margin: EdgeInsets.only(top: 200),
decoration: BoxDecoration(
image: new DecorationImage(
image: AssetImage("assets/fondo.png"), fit: BoxFit.fill)),
),
Image.asset("assets/cara_simio_banner.png"),
Padding(
padding: EdgeInsets.only(top: 220),
child: Text(
"{CodeJaVu}",
style: TextStyle(
color: Colors.white,
fontSize: 25,
fontWeight: FontWeight.bold),
),
),
Container(
margin: EdgeInsets.only(top: 230),
child: GridView.count(
crossAxisCount: 2,
children: items.map((item) {
return GestureDetector(
onTap: () {},
child: CardItem(item),
);
}).toList(),
),
)
],
),
)));
}
Widget CardItem(Item item) {
return Card(
margin: EdgeInsets.all(40),
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(15.0),
),
child:
Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Image.asset(
item.image,
width: 50,
height: 50,
),
Text(item.name)
],
)
);
}
class Item {
String _name;
String _image;
Item(this._name, this._image);
String get name => _name;
set name(String name) => _name = name;
String get image => _image;
set image(String image) => _image = image;
}
what I have,
what I want,

Answer 1

add childAspectRatio parametr to GridView.cout counstructor,
and change Card margin.
I've used:
..
GridView.count(
childAspectRatio: 3/2,
..
Card(
margin: EdgeInsets.symmetric(vertical: 10, horizontal: 20),
..

Answer 2

You can also use mainAxisSpacing and crossAxisSpacing like below.
return GridView.builder(
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 2, crossAxisSpacing: 8, mainAxisSpacing: 4),
padding: EdgeInsets.all(8),
shrinkWrap: true,
itemCount: widgetList.length,
itemBuilder: (context, index) {
return widgetList[index];
},
);

Answer 3

Just add these 2 lines in your GridView widgets:
mainAxisSpacing: 20,
crossAxisSpacing: 20,

Answer 4

children:
space.photos.map((item) {
return Container(
margin: EdgeInsets.only(
left: 24,
),
child: ClipRRect(
borderRadius: BorderRadius.circular(16),
child: Image.network(
item,
width: 110,
height: 88,
fit: BoxFit.cover,
),
),
);
}).toList()