像在 Android GridLayout 中一样围绕单元格的边距

Question

在 Android 中，创建带有下边距的网格列表很容易：

我为 iOS 找到了这个解决方案，但它不会在单元格和父视图之间添加边距，仅在单元格之间添加边距

let itemSpacing: CGFloat = 3
let itemsInOneLine: CGFloat = 2
flow.sectionInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
let width = UIScreen.main.bounds.size.width - itemSpacing * CGFloat(itemsInOneLine - 1) //collectionView.frame.width is the same as  UIScreen.main.bounds.size.width here.
flow.itemSize = CGSize(width: floor(width/itemsInOneLine), height: width/itemsInOneLine)
flow.minimumInteritemSpacing = 3
flow.minimumLineSpacing = 3

我该如何解决？

附：我不想硬编码任何东西，所以它应该适用于所有 iPhone/iPad 设备

Answer 1

let itemSpacing: CGFloat = 3
let itemsInOneLine: CGFloat = 2
let flow = UICollectionView().collectionViewLayout as! UICollectionViewFlowLayout
flow.sectionInset = UIEdgeInsets(top: itemSpacing, left: itemSpacing, bottom: itemSpacing, right: itemSpacing)
flow.minimumInteritemSpacing = itemSpacing
flow.minimumLineSpacing = itemSpacing
let cellWidth = (UIScreen.main.bounds.width - (itemSpacing * 2) - ((itemsInOneLine - 1) * itemSpacing)) / itemsInOneLine
flow.itemSize = CGSize(width: cellWidth, height: cellWidth)

Answer 2

在您的集合视图中添加常量为 5 的前导、尾随和顶部约束。这将解决您的边距问题