UITableViewCell animation in only one direction

Question

I want to animate UITableViewCell only in one direction [down direction]

my code:

 func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
        cell.alpha = 0
         let transform = CATransform3DTranslate(CATransform3DIdentity, 0, 200 , 0)
        cell.layer.transform = transform

        UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 1, initialSpringVelocity: 1, options: .curveEaseOut, animations: {
            cell.alpha = 1
            cell.layer.transform = CATransform3DIdentity
        })
    }

how can i stop that animation [don't perform animation] while user scroll upside?
thanks!!

Please check this answer https://stackoverflow.com/a/43268806/5523205 — Shahrukh, Mar 29 '18 at 11:50

score 1 · Accepted Answer · answered Mar 29 '18 at 12:15

If you have just one section, you can simply compare the current indexPath with the one that was presented as last, and animate only when the new indexPath.row is greater:

fileprivate var lastIndexPath: IndexPath = IndexPath(row: -1, section: 0)

func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {

    // perform animation only when new indexPath.row is greater then the last presented
    if lastIndexPath.row < indexPath.row {
        cell.alpha = 0
        let transform = CATransform3DTranslate(CATransform3DIdentity, 0, 200 , 0)
        cell.layer.transform = transform

        UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 1, initialSpringVelocity: 1, options: .curveEaseOut, animations: {
            cell.alpha = 1
            cell.layer.transform = CATransform3DIdentity
        })
    }

    lastIndexPath = indexPath
}

In case of multiple sections, the approach is the same, just the comparison would be a bit more complicated, because you will have to take sections into account. So instead of:

if lastIndexPath.row < indexPath.row {

You would have to use something like:

if lastIndexPath.section < indexPath.section ||
   (lastIndexPath.section == indexPath.section && lastIndexPath.row < indexPath.row) {

UITableViewCell animation in only one direction

1 Answers1