railingSwipeActionsConfigurationForRowAt导致行滑动，使用swift 4.1根本不平滑

Question

我在tableView中使用TrailingSwipeActionsConfigurationForRowAt，偶尔注意到在向左滑动行以显示操作时，偶尔会出现抖动或断断续续的响应。绝对不流畅。有时，所揭示的动作甚至消失并再次出现。我相信我的函数定义很标准：

override func tableView(_ tableView: UITableView, trailingSwipeActionsConfigurationForRowAt indexPath: IndexPath) -> UISwipeActionsConfiguration? {

    let modelObject = self.fetchedResultsController.object(at: indexPath)

    let deleteAction = UIContextualAction(style: UIContextualAction.Style.normal, title: "Delete") { (action: UIContextualAction, sourceView: UIView, completionHandler: (Bool) -> Void) in

        // set completion to remove displayed actions
        completionHandler(true)

        // delete object here
    }

    let editAction = UIContextualAction(style: UIContextualAction.Style.normal, title: "Edit") { (action: UIContextualAction, sourceView: UIView, completionHandler: (Bool) -> Void) in

        // set completion to remove displayed actions
        completionHandler(true)

        // edit object here

    }

    deleteAction.backgroundColor = UIColor.red
    editAction.backgroundColor = UIColor.gray

    var actions = [UIContextualAction]()

    actions = [deleteAction, editAction]

    let swipeActions = UISwipeActionsConfiguration(actions: actions)
    swipeActions.performsFirstActionWithFullSwipe = false
    return swipeActions
}