如何在没有空间问题情况下创建各种大小的collectionView单元格

import UIKit

class CustomFlowLayout: UICollectionViewFlowLayout {
    override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
        let attributes = super.layoutAttributesForItem(at: indexPath)?.copy() as? UICollectionViewLayoutAttributes
        // 根据indexPath等参数判断当前单元格的位置，并设置对应的单元格大小
        if indexPath.row % 2 == 0 {
            attributes?.size = CGSize(width: 100, height: 100)
        } else {
            attributes?.size = CGSize(width: 200, height: 200)
        }
        return attributes
    }
}

class ViewController: UIViewController, UICollectionViewDataSource {
    private let reuseIdentifier = "Cell"
    private var collectionView: UICollectionView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let layout = CustomFlowLayout()
        collectionView = UICollectionView(frame: view.bounds, collectionViewLayout: layout)
        collectionView.dataSource = self
        collectionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: reuseIdentifier)
        view.addSubview(collectionView)
    }
    
    // MARK: - UICollectionViewDataSource
    
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 10
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath)
        cell.backgroundColor = .red
        return cell
    }
}