因此，正如标题所示，我似乎遇到了一个奇怪的问题。我在这里要做的就是创建一个2列的collectionview，而无需将任何内容硬编码到我的委托方法中。调试后，我发现insetForSectionAt在sizeForItemAt之后被调用，因此在计算每个单元格的大小时不考虑自定义插入。
extension ViewController: UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let flowLayout = collectionView.collectionViewLayout as! UICollectionViewFlowLayout
print("left: ", flowLayout.sectionInset.left) // Prints out 0.0
print("right: ", flowLayout.sectionInset.right) // Prints out 0.0
let marginsAndInsets = flowLayout.sectionInset.left + flowLayout.sectionInset.right + flowLayout.minimumInteritemSpacing * (cellsPerRow - 1)
let itemWidth = (collectionView.bounds.size.width - marginsAndInsets) / cellsPerRow
return CGSize(width: itemWidth, height: itemWidth)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
return UIEdgeInsets(top: 10, left: 10, bottom: 10, right: 10)
}
}
通过将值直接硬编码到itemWidth变量中(例如-20)，可以非常轻松地解决此问题，因为我知道左右inset的值10 + 10
let itemWidth = (collectionView.bounds.size.width - marginsAndInsets - 20) / cellsPerRow
但是，我必须相信有一种更好的方法，如何在UIEdgeInset计算完成后如何调用reloadData以便正确调整单元格的大小？
最佳答案
所以这就是我最终要做的，我只是在为collectionView及其单元格创建尺寸时直接添加了自定义项。
class PinController: UICollectionViewController {
fileprivate let pinCellId = "pinCellId"
fileprivate let cellsPerRow: CGFloat = 2.0
fileprivate let margin: CGFloat = 10.0
fileprivate let topMargin: CGFloat = 2.0
}
extension PinController: UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let flowLayout = customize(collectionViewLayout, margin: margin)
let itemWidth = cellWidth(collectionView, layout: flowLayout, cellsPerRow: cellsPerRow)
return CGSize(width: itemWidth, height: itemWidth * 1.1)
}
/*
Customizes the layout of a collectionView with space to the left and right of each cell that is
specified with the parameter margin
*/
private func customize(_ collectionViewLayout: UICollectionViewLayout, margin: CGFloat) -> UICollectionViewFlowLayout {
let flowLayout = collectionViewLayout as! UICollectionViewFlowLayout
// Interitem spacing affects the horrizontal spacing between cells
flowLayout.minimumInteritemSpacing = margin
// Line spacing affects the vertical space between cells
flowLayout.minimumLineSpacing = margin
// Section insets affect the entire container for the collectionView cells
flowLayout.sectionInset = UIEdgeInsets(top: topMargin, left: margin, bottom: 0, right: margin)
return flowLayout
}
/*
Calculates the proper size of an individual cell with the specified number of cells in a row desired,
along with the layout of the collectionView
*/
private func cellWidth(_ collectionView: UICollectionView, layout flowLayout: UICollectionViewFlowLayout, cellsPerRow: CGFloat) -> CGFloat {
// Calculate the ammount of "horizontal space" that will be needed in a row
let marginsAndInsets = flowLayout.sectionInset.left + flowLayout.sectionInset.right + flowLayout.minimumInteritemSpacing * (cellsPerRow - 1)
let itemWidth = (collectionView.bounds.size.width - marginsAndInsets) / cellsPerRow
return itemWidth
}
}
关于ios - UICollectionViewDelegateFlowLayout Edge嵌入无法被sizeForItemAt函数识别？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/43165636/