swift tvOS vertical scroll Grid - swift

Question

I am new to tvOS development and I would like to create a Grid with 4 items per row. The collection should vertically scroll. My challenge is that I'm not sure what to do with the information provided by Apple here in this doc as there is no example.
In iOS we would use something like:
class GridFlowLayout: UICollectionViewFlowLayout {
// here you can define the height of each cell
let itemHeight: CGFloat = 160
override init() {
super.init()
setupLayout()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
setupLayout()
}
/**
Sets up the layout for the collectionView. 1pt distance between each cell and 1pt distance between each row plus use a vertical layout
*/
func setupLayout() {
minimumInteritemSpacing = 1
minimumLineSpacing = 1
scrollDirection = .vertical
}
var itemWidth: CGFloat {
return collectionView!.frame.width / 4 - 1
}
override var itemSize: CGSize {
set {
self.itemSize = CGSize(width: itemWidth, height: itemHeight)
}
get {
return CGSize(width: itemWidth, height: itemHeight)
}
}
override func targetContentOffset(forProposedContentOffset proposedContentOffset: CGPoint) -> CGPoint {
return collectionView!.contentOffset
}
}
Then assign it to the collectionView layout
collectionView.collectionViewLayout = GridFlowLayout()
Im not sure what to do for tvOS how should I adapt the above code to work for tvOS using programmatic code.