UICollectionView crashes when column count changes - ios

Question

I have a UICollectionview and the number of columns are changing randomly. Every time the column count changes I invoke the following function.
func setTheCollectionViewSize(){
if self.activeLockerList.count > 0 {
self.btnLockerDropdown.setTitle("Lockers Set \(self.activeLockerList[0].lockerId)", for: UIControlState.normal)
}
screenSize = UIScreen.main.bounds
screenWidth = screenSize.width
screenHeight = screenSize.height
//if the collection view layout is not invalidated then the app will crash
let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
layout.minimumInteritemSpacing = 0
layout.minimumLineSpacing = 0
//setting the collectionview size so there will be no white lines in the drawn boxes
var appropriateScreenWidth = Int(self.screenWidth)
while appropriateScreenWidth % Int(self.numberOfLockersPerColumn) != 0 {
appropriateScreenWidth = appropriateScreenWidth - 1
}
let itemWidth : CGFloat = CGFloat(appropriateScreenWidth) / self.numberOfLockersPerColumn
collectionViewWidthLocal.constant = CGFloat(appropriateScreenWidth)
layout.itemSize = CGSize(width: itemWidth, height: itemWidth)
print(self.numberOfLockersPerColumn)
print(screenWidth)
layout.minimumInteritemSpacing = 0
layout.minimumLineSpacing = 0
layout.sectionInset = UIEdgeInsets(top: 10.0, left: 0, bottom: 10.0, right: 0)
self.collectionView.collectionViewLayout.invalidateLayout()
self.collectionView.setCollectionViewLayout(layout, animated: false)
}
When the cell count for each row increases it works fine. But when the count decreases app crashes at the line self.collectionView.setCollectionViewLayout(layout, animated: false)
As you can see invalidating the collectionview with self.collectionView.collectionViewLayout.invalidateLayout() also didn't help. I've been spending hours and hours still without luck. Thanks in advance.

Answer 1

Did you invoke setTheCollectionViewSize() function before collectionView.reloadData() or after?
It should go in the following order. Try and let me know.
self.collectionView.reloadData()
self.setTheCollectionViewSize()
in other words following should be the order when invalidating collectionview
self.collectionView.reloadData()
self.collectionView.collectionViewLayout.invalidateLayout()
Hope it helps you out.