ListViewAutoSizeBehavior.cs

namespace Xamarin.Forms
{
  public class AutoSizeBehavior : Behavior<ListView>
  {
    ListView _ListView;

    protected override void OnAttachedTo(ListView bindable)
    {
      _ListView = bindable;
      bindable.HeightRequest = 0;
      bindable.ItemAppearing += AppearanceChanged;
      bindable.ItemDisappearing += AppearanceChanged;
    }

    protected override void OnDetachingFrom(ListView bindable)
    {
      bindable.ItemAppearing -= AppearanceChanged;
      bindable.ItemDisappearing -= AppearanceChanged;
      _ListView = null;
    }

    private void AppearanceChanged(object sender, ItemVisibilityEventArgs e) =>
      UpdateHeight(e.Item);

    void UpdateHeight(object item)
    {
      double height;
      if (_ListView.HasUnevenRows)
      {
        if ((height = _ListView.HeightRequest) == (double)VisualElement.HeightRequestProperty.DefaultValue)
          height = 0;

        height += MeasureRowHeight(item);
      }
      else
      {
        height = _ListView.RowHeight;
        if (height == (int)ListView.RowHeightProperty.DefaultValue)
          _ListView.RowHeight = (int)(height = MeasureRowHeight(item));
      }
      SetHeight(height);
    }

    double MeasureRowHeight(object item)
    {
      var template = _ListView.ItemTemplate;
      var cell = (Cell)template.CreateContent();
      cell.BindingContext = item;

      // TODO: redundant
      cell.ForceUpdateSize();

      var height = cell.RenderHeight;
      var mod = height % 1;
      if (mod > 0)
        height = height - mod + 1;
      return height;
    }

    void SetHeight(double rowHeight)
    {
      var height = 0d;
      // TODO if header or footer is string etc.
      if (_ListView.Header is VisualElement header)
        height += header.Height;
      if (_ListView.Footer is VisualElement footer)
        height += footer.Height;

      var tiv = (ITemplatedItemsView<Cell>)_ListView;
      height += tiv.TemplatedItems.Count * rowHeight;

      _ListView.HeightRequest = height;
    }
  }
}

In the 'MeasureRowHeight' method, cell.RenderHeight always returns 40 for me irrespective of cell content. So no matter how the cell content is it always returns fixed height of the ListView. Any idea what could be wrong?

I'm facing the same issue as @krunalc

same, not working when HasUnevenRow is true

why to check for _ListView.HasUnevenRows just do this
void UpdateHeight(object item)
{
double height;
if ((height = _ListView.HeightRequest) == (double)VisualElement.HeightRequestProperty.DefaultValue)
height = 0;
height += MeasureRowHeight(item);
SetHeight(height);
}
it will work fine with number of rows with height set for viewcell