UICollectionView stopped showing cells after upgrading minimum deployment target to iOS 14 - ios

Question

I have screen with two large UICollectionViewCells. Using XIB as Interface Builder. UICollectionView DataSource and Delegate is connected to my UIViewController that contains it.
Installed checkmark is true. isHidden is false. Alpha 1 for cells and UICollectionView. Also I've registered cells for UICollectionView with correct identifiers.
Before I've updated my project from minimum deployment target iOS 13 - UICollectionView works fine. After upgrading to iOS 14 minimum deployment - UICollectionView doesn't show cells. If I return minimum deployment to iOS 13 without any codebase changes - works fine.
Please anyone safe my time as I've wasted whole day already with no luck! Thanks in advance!

Answer 1

So I found the reason of this very strange bug. My goal was to create UICollectionView with cell which contain flexible UITextField. While user is writing - cell changes its size regarding to text height in text field.
To implement it I was using these configurations for my UICollectionView:
Image with UICollectionView configurations
Here You can see that "Cell Size" width is 0, and "Estimate Size" is automatic. It is configured for flexible cell height.
To make it work I have added this code also:
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
guard let flowLayout = collectionView.collectionViewLayout as? UICollectionViewFlowLayout,
flowLayout.estimatedItemSize.width == .greatestFiniteMagnitude else {
return
}
flowLayout.estimatedItemSize = CGSize(
width: view.frame.width - Size.verticalCollectionInsetsDistance * 2,
// Make the height a reasonable estimate to
// ensure the scroll bar remains smooth
height: 200
)
}
And here is a trick:
When I had upgraded my app to iOS 14 minimum deployment this code is broken. Because, for some reason, when You set "Cell Size" width to 0 and you have iOS 13 minimum deployment, then estimatedItemSize.width == .greatestFiniteMagnitude is true. But for iOS 14 estimatedItemSize.width == .greatestFiniteMagnitude is false and estimatedItemSize.width == 0 is true instead. So now I've fixed my code by adding this condition "flowLayout.estimatedItemSize.width == 0". And here is final version:
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
guard let flowLayout = collectionView.collectionViewLayout as? UICollectionViewFlowLayout,
flowLayout.estimatedItemSize.width == .greatestFiniteMagnitude || flowLayout.estimatedItemSize.width == 0 else {
return
}
flowLayout.estimatedItemSize = CGSize(
width: view.frame.width - Size.verticalCollectionInsetsDistance * 2,
// Make the height a reasonable estimate to
// ensure the scroll bar remains smooth
height: 200
)
}
P.S. I still don't understand why iOS 14 estimatedItemSize.width is different then iOS 13. If You know answer please describe it in comments. Thanks in advance!