Using long press gesture to reorder cells in tableview?

Question

I want to be able to reorder tableview cells using a longPress gesture (not with the standard reorder controls). After the longPress is recognized I want the tableView to essent

Answer 1

Swift 3 and no third party solutions

First, add these two variables to your class:

var dragInitialIndexPath: IndexPath?
var dragCellSnapshot: UIView?

Then add UILongPressGestureRecognizer to your tableView:

let longPress = UILongPressGestureRecognizer(target: self, action: #selector(onLongPressGesture(sender:)))
longPress.minimumPressDuration = 0.2 // optional
tableView.addGestureRecognizer(longPress)

Handle UILongPressGestureRecognizer:

// MARK: cell reorder / long press

func onLongPressGesture(sender: UILongPressGestureRecognizer) {
  let locationInView = sender.location(in: tableView)
  let indexPath = tableView.indexPathForRow(at: locationInView)

  if sender.state == .began {
    if indexPath != nil {
      dragInitialIndexPath = indexPath
      let cell = tableView.cellForRow(at: indexPath!)
      dragCellSnapshot = snapshotOfCell(inputView: cell!)
      var center = cell?.center
      dragCellSnapshot?.center = center!
      dragCellSnapshot?.alpha = 0.0
      tableView.addSubview(dragCellSnapshot!)

      UIView.animate(withDuration: 0.25, animations: { () -> Void in
        center?.y = locationInView.y
        self.dragCellSnapshot?.center = center!
        self.dragCellSnapshot?.transform = (self.dragCellSnapshot?.transform.scaledBy(x: 1.05, y: 1.05))!
        self.dragCellSnapshot?.alpha = 0.99
        cell?.alpha = 0.0
      }, completion: { (finished) -> Void in
        if finished {
          cell?.isHidden = true
        }
      })
    }
  } else if sender.state == .changed && dragInitialIndexPath != nil {
    var center = dragCellSnapshot?.center
    center?.y = locationInView.y
    dragCellSnapshot?.center = center!

    // to lock dragging to same section add: "&& indexPath?.section == dragInitialIndexPath?.section" to the if below
    if indexPath != nil && indexPath != dragInitialIndexPath {
      // update your data model
      let dataToMove = data[dragInitialIndexPath!.row]
      data.remove(at: dragInitialIndexPath!.row)
      data.insert(dataToMove, at: indexPath!.row)

      tableView.moveRow(at: dragInitialIndexPath!, to: indexPath!)
      dragInitialIndexPath = indexPath
    }
  } else if sender.state == .ended && dragInitialIndexPath != nil {
    let cell = tableView.cellForRow(at: dragInitialIndexPath!)
    cell?.isHidden = false
    cell?.alpha = 0.0
    UIView.animate(withDuration: 0.25, animations: { () -> Void in
      self.dragCellSnapshot?.center = (cell?.center)!
      self.dragCellSnapshot?.transform = CGAffineTransform.identity
      self.dragCellSnapshot?.alpha = 0.0
      cell?.alpha = 1.0
    }, completion: { (finished) -> Void in
      if finished {
        self.dragInitialIndexPath = nil
        self.dragCellSnapshot?.removeFromSuperview()
        self.dragCellSnapshot = nil
      }
    })
  }
}

func snapshotOfCell(inputView: UIView) -> UIView {
  UIGraphicsBeginImageContextWithOptions(inputView.bounds.size, false, 0.0)
  inputView.layer.render(in: UIGraphicsGetCurrentContext()!)
  let image = UIGraphicsGetImageFromCurrentImageContext()
  UIGraphicsEndImageContext()

  let cellSnapshot = UIImageView(image: image)
  cellSnapshot.layer.masksToBounds = false
  cellSnapshot.layer.cornerRadius = 0.0
  cellSnapshot.layer.shadowOffset = CGSize(width: -5.0, height: 0.0)
  cellSnapshot.layer.shadowRadius = 5.0
  cellSnapshot.layer.shadowOpacity = 0.4
  return cellSnapshot
}