Programmatically Position Views in RelativeLayout
public override View  GetView(int position, View convertView, ViewGroup parent)
    {
        RelativeLayout rl = new RelativeLayout(context);
        RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.FillParent, ViewGroup.LayoutParams.FillParent);
        ImageView imageView;
        TextView tv;

        imageView = new ImageView(context);
        imageView.LayoutParameters = new GridView.LayoutParams(250, 250);
        imageView.SetScaleType(ImageView.ScaleType.CenterCrop);
        imageView.SetPadding(8, 8, 8, 8);
        imageView.SetImageResource(thumbIds[position]);
        imageView.Id = position;

        lp.AddRule(LayoutRules.Below, position);
        lp.AddRule(LayoutRules.CenterHorizontal);

        tv = new TextView(context);
        tv.Text = stringIds[position].ToString();
        tv.SetTextSize(Android.Util.ComplexUnitType.Dip, 20);
        tv.SetTextColor(Android.Graphics.Color.WhiteSmoke);
        tv.LayoutParameters = lp;

        rl.AddView(imageView);
        rl.AddView(tv);

        return rl;
    }