UICollectionView cell spacing not working anymore - ios

Question

I have been working on this app for a few days, I am working on laying out a UICollectionView to appear like a grid with no spacing in between the cells. It was working fantastically after I found this answer and implemented it into my own program. I worked on some other files and updated my computer, then I came back and tested this app just to see where I was and for some reason there is horizontal spacing in between cells. I have looked at a few other questions similar to this one, but I'm just wondering how to fix this and why this happened when I didn't change anything related to the layout.
Here's is what it looks like now:
import UIKit
class ViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {
#IBOutlet weak var collectionView: UICollectionView!
var model = BoardModel()
var board = Board()
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
collectionView.delegate = self
collectionView.dataSource = self
board = model.newGame(4, 4)
// Remove the spacing between the cells in collectionView
// Also make the cells the correct size to form a square/rectangle
let screenSize: CGRect! = collectionView.bounds
let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
layout.sectionInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
layout.itemSize = CGSize(width: screenSize.width/CGFloat(board.columns), height: screenSize.width/CGFloat(board.columns))
layout.minimumInteritemSpacing = 0
layout.minimumLineSpacing = 0
collectionView!.collectionViewLayout = layout
// Center the collectionView
collectionView.contentInset.top = max((collectionView.frame.height - collectionView.contentSize.height) / 5, 0)
}
The reason I'm using the collectionView bounds instead of the UIScreen.mainScreen().bounds is because my collectionView has 20 spacing around all the edges.

Answer 1

Can you try
let width = UIScreen.main.bounds.width - 40 // convert it if it's not swift 4
let height = UIScreen.main.bounds.height - 40
//
or implement
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize.init(width: , height: )
}

Answer 2

import UIKit
class ViewController: UIViewController {
fileprivate let sectionInsets = UIEdgeInsets(top: 5.0, left: 5.0, bottom: 5.0, right: 5.0)
fileprivate let itemsPerRow: CGFloat = 2
override func viewDidLoad() {
super.viewDidLoad()
}
}
// MARK: UICollectionViewDelegateFlowLayout
extension ViewController : UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize{
let paddingSpace = sectionInsets.left * (itemsPerRow + 1)
let availableWidth = view.frame.width - paddingSpace
let widthPerItem = availableWidth / itemsPerRow
let heightPerItem = widthPerItem + 21
return CGSize(width: widthPerItem, height: heightPerItem)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets{
return sectionInsets
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat{
return sectionInsets.left
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat{
return 0
}
}