ios - 使用混合分数和绝对值来调整 NSCollectionLayoutItem 的大小

Question

我正在调整NSCollectionLayoutItem其组中的一个。使用NSCollectionLayoutSize并且NSCollectionLayoutDimension我可以实现诸如'<em>我希望它是其容器宽度的一半'或'我希望它是 200px ' 或'<em>我希望它的高度与它的宽度相同的要求加10%'。

但我找不到实现我需要的方法：'<em>我希望它的高度与它的宽度相同，再加上 28px'。

这有可能吗？

代码：

private lazy var myFancyLayout: NSCollectionLayoutSection = {
        let itemSize = NSCollectionLayoutSize(
            widthDimension: .fractionalWidth(1.0),
            heightDimension: .fractionalWidth(1.0)
        )
        let item = NSCollectionLayoutItem(layoutSize: itemSize)
        
        // Make the group with width equal to half container width and with height 110% its width
        let groupSize_fractional = NSCollectionLayoutSize(
            widthDimension: .fractionalWidth(0.50),
            heightDimension: .fractionalWidth(0.50 * 1.1)
        )
        
        // Make the group with width equal to 100px and with height 110% its width
        let groupSize_absoulte = NSCollectionLayoutSize(
            widthDimension: .absolute(100),
            heightDimension: .absolute(100 * 1.1)
        )
        
        // Make the group with width equal to half container width and with height same as its width plus 20px
        let groupSize_mixed_impossibleToImplement = NSCollectionLayoutSize(
            widthDimension: .fractionalWidth(0.50),
            heightDimension: .fractionalWidth(0.50) // + 20px ??
        )
        
        let group = NSCollectionLayoutGroup.horizontal(
            layoutSize: groupSize_fractional, // or groupSize_absoulte or groupSize_mixed_impossibleToImplement
            subitem: item,
            count: 1
        )

        let section = NSCollectionLayoutSection(group: group)
        
        // ... further configuration
        
        return section
}()