Custom UICollectionViewCell size in Swift 4.2 - swift

Question

I am working on a crossword app but I keep missing something when I calculate each itemSize of the UICollectionView. I get the right size for iPhone SE but the wrong size for iPhone XR. What am I doing wrong?
func setLayout() -> UICollectionViewFlowLayout {
let layout = UICollectionViewFlowLayout()
layout.itemSize = getCellSize()
layout.minimumInteritemSpacing = 0
layout.minimumLineSpacing = 0
layout.sectionInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
return layout
}
func getCellSize() -> CGSize {
let width:CGFloat = self.view.frame.width/CGFloat(crossWordData[0].count)
let height:CGFloat = (self.view.frame.height - TitleView.frame.height)/CGFloat(crossWordData.count) - cellsBorderWidth
//cellsBorderWidth = 1.2
let cellSize = CGSize(width:width , height:height)
return cellSize
}

Answer 1

This is because self.view ends where is bottom of the display. New iPhones (X, Xs, Xs Max, Xr) have on the bottom this place for "home gesture". So for your calculation, content of your CollectionView is bigger than CollectionView because your CollectionView has bottom constraint equal to safe area bottom constraint which is for new iPhones higher than where bottom of the display is. So when you need width and height instead of this
let width:CGFloat = self.view.frame.width/CGFloat(crossWordData[0].count)
let height:CGFloat = (self.view.frame.height - TitleView.frame.height)/CGFloat(crossWordData.count) - cellsBorderWidth
call this
let width:CGFloat = self.yourCollectionView.frame.width/CGFloat(crossWordData[0].count)
let height:CGFloat = self.yourCollectionView.frame.height/CGFloat(crossWordData.count) - cellsBorderWidth

Answer 2

Eventually this is how I changed my code -
let width:CGFloat = self.view.frame.width/CGFloat(crossWordData[0].count)
let height:CGFloat = self.view.frame.height*0.85/CGFloat(crossWordData.count)
The collections view height is 85% in the screen layout