ios - 如何确定自定义UICollectionViewCell在屏幕上何时为100％

从上图中，我有带有4个自定义单元格的UICollectionView。任何时候，屏幕上都可以显示2或3个单元格。如何确定“单元格1”或“单元格2”何时在屏幕上为100％？

两个都

collectionView.visibleCells
collectionView.indexPathsForVisibleItems

返回数组，并且不会告诉您屏幕上哪个单元格是否为100％。

如果是图片，将在didSelectItemAt上显示以下内容
collectionView.visibleCells

[<Shot_On_Goal.MainCollectionViewCell: 0x101f525c0; baseClass = UICollectionViewCell; frame = (190 7.66667; 454 350); clipsToBounds = YES; opaque = NO; layer = <CALayer: 0x1c0237300>>, <Shot_On_Goal.HeaderCollectionViewCell: 0x101f4d580; baseClass = UICollectionViewCell; frame = (10 0; 170 365); clipsToBounds = YES; opaque = NO; layer = <CALayer: 0x1c0236800>>, <Shot_On_Goal.TheirHockeyNetCollectionViewCell: 0x101f55520; baseClass = UICollectionViewCell; frame = (654 7.66667; 454 350); clipsToBounds = YES; opaque = NO; layer = <CALayer: 0x1c0238fe0>>]

collectionView.indexPathsForVisibleItems

[[0, 1], [0, 0], [0, 2]]

最佳答案

这将为完全可见的单元格返回一个IndexPaths数组:

func fullyVisibleCells(_ inCollectionView: UICollectionView) -> [IndexPath] {

    var returnCells = [IndexPath]()

    var vCells = inCollectionView.visibleCells
    vCells = vCells.filter({ cell -> Bool in
        let cellRect = inCollectionView.convert(cell.frame, to: inCollectionView.superview)
        return inCollectionView.frame.contains(cellRect)
    })

    vCells.forEach({
        if let pth = inCollectionView.indexPath(for: $0) {
            returnCells.append(pth)
        }
    })

    return returnCells

}

@IBAction func test(_ sender: Any) {

    let visCells = fullyVisibleCells(self.collectionView)
    print(visCells)

}

关于ios - 如何确定自定义UICollectionViewCell在屏幕上何时为100％，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/46829901/