Table view cell load animation one after another

Question

I need to animate the load of the table view rows. When the table reloads the data I need the rows get in from the left one after another. How can I achieve this?

Answer 1

Swift 4

I made a quick extension on UITableView to animate cells:

tableView.reloadData() // To make sure tableView.visibleCells is not empty

tableView.animateCells(
      cells: tableView.visibleCells,
      duration: 0.3,
      delay: 0.5,
      dampingRatio: 0.8,
      configure: { cell -> (prepare: () -> Void, animate: () -> Void)? in
        guard let customCell = cell as? CustomCell else { return nil }
        let preparations = {
          customCell.iconImageView.alpha = 0
        }
        let animations = {
          customCell.iconImageView.alpha = 1
        }
        return (preparations, animations)
    }, completion: {
      print("Cell animations are completed")
    })

The extension looks like this:

extension UITableView {
  func animateCells(cells: [Cell],
                                           duration: TimeInterval,
                                           delay: TimeInterval = 0,
                                           dampingRatio: CGFloat = 0,
                                           configure: @escaping (Cell) -> (prepare: () -> Void, animate: () -> Void)?,
                                           completion: @escaping () -> Void) {
    var cellDelay: TimeInterval = 0
    var completionCount: Int = 0

    for cell in cells {
      if let callbacks = configure(cell) {
        callbacks.prepare()

        let animator = UIViewPropertyAnimator(duration: duration, dampingRatio: dampingRatio)

        animator.addAnimations(callbacks.animate)

        let completionTime = cellDelay + (duration * TimeInterval(dampingRatio))

        DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + completionTime) {
          completionCount += 1
          if completionCount == cells.count {
            completion()
          }
        }

        animator.startAnimation(afterDelay: cellDelay)

        cellDelay += delay
      } else {
        completionCount += 1
      }
    }
  }
}