How to determine when a custom UICollectionViewCell is 100% on the screen

This will return an Array of IndexPaths for the fully visible cells:

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)}

Here's an extension for it, based don DonMag's answer:

extension UICollectionView {    var fullyVisibleCells : [UICollectionViewCell] {        return self.visibleCells.filter { cell in            let cellRect = self.convert(cell.frame, to: self.superview)            return self.frame.contains(cellRect) }    }}

You can filter your visibleCells array to check if the frame of your cell is included in the frame of your collectionView:

    var visibleCells = self.collectionView?.visibleCells    visibleCells = visibleCells?.filter({ cell -> Bool in        return self.collectionView?.frame.contains(cell.frame) ?? false    })    print (visibleCells)