[ASCellNode] Verify implementation of manual de-selection.

[appleguy]

See commentary in:

#837

[appleguy]

cc @levi, @vitalybaev

[haashem]

@appleguy thanks for trying to fix the bug, bug still exists! and another bug created!
here is how I select cells.

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
    HAMenuItemCell *cell = (HAMenuItemCell *)[self.collectionView nodeForItemAtIndexPath:indexPath];
    if (cell.selected) {
        cell.selected = NO;
    }
    else
        cell.selected = YES;
}

then when I scroll down or up without selected cell being disappeared, setSelected:Yes gets called multiple times!
sample app

and here is the new bug:

[levi]

@hashemp206 try depending on the default behavior of the selected property of ASCellNode automatically being set by the selection behavior of UICollectionView. Setting cell.selected = YES is where you multiple call issue is coming from.

[levi]

@HannahBannana this is something that I think fell through the cracks last year. Could you take a look when you have a spare moment?

[levi]

Oops, @hannahmbanana

[hannahmbanana]

There is definitely an issue with setSelected: getting called multiple times here even after excluding the aforementioned manual cell selection code. I interpret the UIKit documentation as saying that they don't do anything in -prepareForReuse, however it appears that UICollectionViewCells have their selected and highlighted states reset when preparing for reuse. I'm not sure of the idea way to resolve this without multiple calls being made, but I'll take a deeper look tomorrow.

[hannahmbanana]

Related: #860

[levi]

@hannahmbanana thanks for looking into this. I recall testing this behavior on a vanilla UICollectionView and multiple call were being made. Definitely double check that when diagnosing this. Thanks!

[hannahmbanana]

@hashemp206: I apologize that it took us a few months to get around to investigating this incorrect behavior. PR #1816 should fix this issue! If you are still using the framework, try it out and let us know if it works for you.