不使用二维数组的swift UICollectionView区段分离

import UIKit

class CustomFlowLayout: UICollectionViewFlowLayout {
    
    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
        let attributes = super.layoutAttributesForElements(in: rect)
        
        var newAttributes = [UICollectionViewLayoutAttributes]()
        
        for attribute in attributes ?? [] {
            if attribute.representedElementCategory == .cell {
                let indexPath = attribute.indexPath
                let newIndexPath = IndexPath(item: indexPath.item, section: 0)
                let newAttribute = UICollectionViewLayoutAttributes(forCellWith: newIndexPath)
                newAttribute.frame = attribute.frame
                newAttributes.append(newAttribute)
            } else {
                newAttributes.append(attribute)
            }
        }
        
        return newAttributes
    }
    
    override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
        let newIndexPath = IndexPath(item: indexPath.item, section: 0)
        return super.layoutAttributesForItem(at: newIndexPath)
    }
    
    override func shouldInvalidateLayout(forBoundsChange newBounds: CGRect) -> Bool {
        return true
    }
}

let layout = CustomFlowLayout()
let collectionView = UICollectionView(frame: CGRect(x: 0, y: 0, width: 300, height: 200), collectionViewLayout: layout)