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SelectedBackgroundView from UICollectionViewCell is displayed when it shouldn't be

I have a UICollectionView. With some cells inside with a white background color. I have set selectedBackgroundView to base purple view.

My CollectionView has a limit with a height of 0, and when I click the button, I update the limit to 80. When I do this, during the animation, I can see the purple background on the screen all the way to the end on and I can't figure out why or how to prevent it ? Everything else works fine, it's just a "visual" error. Any suggestion on how to fix this?

Gif error where you can see purple appearing during animation Visual bug

Here is my cell design, if it can help:

    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    var cell = collectionView.dequeueReusableCellWithReuseIdentifier("WidgetMenuCellIdentifier", forIndexPath: indexPath) as UICollectionViewCell

    cell.removeSubviews()

    // some code setup

    cell.selectedBackgroundView = UIView()
    cell.selectedBackgroundView.backgroundColor = UIColor.purpleColor()

    return cell
}
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2 answers


  • Subclassing your UICollectionViewCell

  • Do

    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {

// your code
cell.selectedBackgroundView.hidden = true

return cell
}

  • Then in your subclass

    override var selected:Bool {
   willSet {
       self.selectedBackgroundView.hidden = false
   }
}


It should work.

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This code appears to be executing in animation, resulting in unexpected timing behavior based on how various properties animate. Another complicating factor is that since the cells are reused it will not play if the reused cell is already set up correctly (i.e. nothing to animate). Adding the following after styling selectedBackgroundView

was the least dangerous solution I could think of.

[cell.selectedBackgroundView.layer removeAllAnimations];


Depending on your cells, you might also consider removing animations at other levels. For example:

[cell.backgroundView.layer removeAllAnimations];
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