Flutter - How to display a GridView within an AlertDialog box?

Question

I'm trying to display a GridView of images to allow a user to pick from within a Dialog Box and I'm having rendering issues. My UI fades as if a view was appearing on top of it, but nothing displays. Here is my code...

Future<Null> _neverSatisfied() async {
    return showDialog<Null>(
      context: context,
      barrierDismissible: false, // user must tap button!
      child: new AlertDialog(
        title: new Text(
          'SAVED !!!',
          style:
          new TextStyle(fontWeight: FontWeight.bold, color: Colors.black),
        ),
        content: new GridView.count(
            crossAxisCount: 4,
            childAspectRatio: 1.0,
            padding: const EdgeInsets.all(4.0),
            mainAxisSpacing: 4.0,
            crossAxisSpacing: 4.0,
            children: <String>[
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
            ].map((String url) {
              return new GridTile(
                  child: new Image.network(url, fit: BoxFit.cover, width: 12.0, height: 12.0,));
            }).toList()),
        actions: <Widget>[
          new IconButton(
              splashColor: Colors.green,
              icon: new Icon(
                Icons.done,
                color: Colors.blue,
              ),
              onPressed: () {
                Navigator.of(context).pop();
              })
        ],
      ),
    );
  }

Answer 1

The issue is that, the AlertDailog tries to get the intrinsic width of the child. But GridView being lazy does not provide intrinsic properties. Just try wrapping the GridView in a Container with some width.

Example:

Future<Null> _neverSatisfied() async {
  return showDialog<Null>(
    context: context,
    barrierDismissible: false, // user must tap button!
    child: new AlertDialog(
      contentPadding: const EdgeInsets.all(10.0),
      title: new Text(
        'SAVED !!!',
        style:
        new TextStyle(fontWeight: FontWeight.bold, color: Colors.black),
      ),
      content: new Container(
        // Specify some width
        width: MediaQuery.of(context).size.width * .7,
        child: new GridView.count(
            crossAxisCount: 4,
            childAspectRatio: 1.0,
            padding: const EdgeInsets.all(4.0),
            mainAxisSpacing: 4.0,
            crossAxisSpacing: 4.0,
            children: <String>[
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
              'http://www.for-example.org/img/main/forexamplelogo.png',
            ].map((String url) {
              return new GridTile(
                  child: new Image.network(url, fit: BoxFit.cover, width: 12.0, height: 12.0,));
            }).toList()),
      ),
      actions: <Widget>[
        new IconButton(
            splashColor: Colors.green,
            icon: new Icon(
              Icons.done,
              color: Colors.blue,
            ),
            onPressed: () {
              Navigator.of(context).pop();
            })
      ],
    ),
  );
}

You can read more about how intrinsic properties are calculated for different views here.

Hope that helps!