CollectionView Custom Layout

HomeCustomLayout.swift

import UIKit

enum CollectionDisplay {
    case list
    case twoColumns
}

class HomeCustomLayout: c {
    
    var cellHeight: CGFloat = 100
    
    var display: CollectionDisplay = .twoColumns {
        didSet {
            if display != oldValue {
                self.invalidateLayout()
            }
        }
    }
    
    convenience init(display: CollectionDisplay) {
        self.init()
        self.display = display
        self.minimumLineSpacing = 10
        self.minimumInteritemSpacing = 10
        self.configLayout()
    }
    
    func configLayout() {
        switch display {
        case .twoColumns:
            self.itemSize = getGridSize()
        case .list:
            self.itemSize = getListSize()
        }
    }

    func getGridSize() -> CGSize {
        guard let collectionView = self.collectionView else { return .zero }
        let squareWidth = (collectionView.frame.width - minimumInteritemSpacing) / 2
        return CGSize(width: squareWidth , height: squareWidth)
    }
    
    func getListSize() -> CGSize {
        guard let collectionView = self.collectionView else { return .zero }
        return CGSize(width: collectionView.frame.width , height: cellHeight)
    }
    
    override func invalidateLayout() {
        super.invalidateLayout()
        self.configLayout()
    }

}