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POLarge UICollectionViewCell stopped being displayed when scrolling
 

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    <p>The same behavior of <code>UICollectionView</code> as described here has been led to <a href="https://stackoverflow.com/questions/13016302/large-cells-in-a-uicollectionview-getting-removed-while-the-cell-is-still-displa">this question</a>. Even though I decided to post my own one, because I did further investigations, I didn't want to post in a comment or in edit of the question mentioned above.</p> <p><strong>What happens?:</strong></p> <p>When large cells being displayed in a <code>UICollectionView</code> with a <code>UICollectionViewFlowLayout</code>, after scrolling the collection view to a certain offset, the cells will disappear.</p> <p>When scrolling further until another cell comes into visible area, the vanished/hidden cell becomes visible again. </p> <p>I tested with a vertical scrolling collection view and full-width-cells, but I'm rather sure, that it would also happen with similar setups for horizontal scrolling.</p> <p><strong>What are large cells?:</strong></p> <p>The described behavior happens with cells higher than twice the display height (<code>960.f + 1.f</code> on 3,5 inch displays, <code>1136.f + 1.f</code> on 4 inch).</p> <p><strong>What <em>exactly</em> happens?:</strong></p> <p>When the scrolling offset of the collection view exceeds <code>cell.frame.origin.y + displayHeightOfHardware</code> the cells hidden property is set to <code>YES</code> and <code>-collectionView:didEndDisplayingCell:forItemAtIndexPath:</code> gets called (e.g. the first cell changes to hidden when <code>scrollingOffset.y</code> reaches <code>481.f</code> on 3,5-inch-iPhone).</p> <p>As described above, when scrolling until next cell comes into view, the hidden cell gets displayed again (i.e. hidden property changes to <code>NO</code>) and furthermore, when scrolling far enough the cell will never vanish again, when it shouldn't, no matter where you scroll to.</p> <p>This changes when working with cells larger than triple-display-height (<code>1441.f/1705.f</code>). Those show the same behavior, but it stays the same, no matter how far they're being scrolled up and down.</p> <p><strong>What else?:</strong></p> <p>The situation can not be fixed by overriding <code>-(BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds</code> to return <code>YES</code>.</p> <p>The cells cannot being forced to display with setting the hidden property to <code>NO</code> programmatically after they were hidden (in <code>didEndDisplayingCell</code> for example) </p> <p><strong>So, whats the question?:</strong></p> <p>I'm pretty sure, that this is a bug in <code>UICollectionView/Controller/Cell/Layout</code> and I'll submit a TSI at Apple. But for the meantime: <strong>Has anyone any ideas for a quick hack solution</strong>?</p>
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