NSException when deleting UITableViewCell

Question

I am using the open-source library on Github MGSwipeTableCell (https://github.com/MortimerGoro/MGSwipeTableCell) for revealing buttons when swiping cells of a table view.

A crash occurs when I tap a button revealed by swiping. I define the closure that should be invoked when tapping the button here:

// This is in the library delegate method:
// func swipeTableCell(_ cell: MGSwipeTableCell, swipeButtonsFor direction: MGSwipeDirection, swipeSettings: MGSwipeSettings, expansionSettings: MGSwipeExpansionSettings) -> [UIView]?

// local variables: buttons, one of which is:
let rejectFriendReqButton = MGSwipeButton(title: "", icon: UIImage(named: "X"), backgroundColor: RED) { (cell) -> Bool in

    DispatchQueue.main.async(execute: {
        self.friendListTableView.deleteRows(at: [self.friendListTableView.indexPath(for: cell)!], with: .fade)
    })

    return FriendingCloudKitUtils.declineFriendRequest()
}

// In an if-else ladder:
else if direction == MGSwipeDirection.rightToLeft { // reject friend request

    if section == 2 { // friend requests

        if direction == MGSwipeDirection.leftToRight { // accept friend request
            return [acceptFriendReqButton]
        }

        else if direction == MGSwipeDirection.rightToLeft { // reject friend request

            return [rejectFriendReqButton]
        }
    }
    else if self.friendListTableView.indexPath(for: cell)?.section == 4 { // in friend section
        return [unfriendButton]
    }
}

The crash occurs at the line where I call deleteRows. I get an NSException. When I execute po $arg1 in lldb, I get:

error: Couldn't materialize: couldn't read the value of register x0
error: errored out in DoExecute, couldn't PrepareToExecuteJITExpression

I've tried more possible solutions than I can keep track of, among them storing the button as a global variable instead of a local one.

Other potentially relevant notes:

When I go into debug mode, the table does indeed exist:

<UITableView: 0x10186c000; frame = (0 0; 375 554); clipsToBounds = YES; autoresize = RM+BM; gestureRecognizers = <NSArray: 0x17425a760>; layer = <CALayer: 0x174236760>; contentOffset: {0, 0}; contentSize: {375, 357.5}>

The indexPath that is being unwrapped also isn't nil and has the correct section and row numbers:

lldb) po self.friendListTableView.indexPath(for: cell)!
▿ 2 elements
  - 0 : 2
  - 1 : 0

Any ideas on what is causing this NSException and how I might fix it?

Answer 1

    self.friendListTableView.beginUpdates()
    your_dataSource.remove(at: self.friendListTableView.indexPath(for: cell)!)
    self.friendListTableView.deleteRows(at: [self.friendListTableView.indexPath(for: cell)!])
    self.tableView.endUpdates()

In order to delete the row from tableView with animation, modify the data source first and then call deleteRows. Finally wrap the delete code in beginUpdates and endUpdates

Answer 2

If you want to delete row just simply find the value of indexPath of that row and call this method

 func tableView(_ tableView: UITableView, commit editingStyle: 
               UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {    

  if editingStyle == .delete {
       print("Deleted")
      your_dataSource.remove(at: indexPath.row)
      self.tableView.deleteRows(at: [indexPath], with: .automatic)
  }
 }

It will handle your delete row operation.