Swift - TableView Assert Error: cellForRowAtIndexPath Because of: canEditRowAt()

Question

Using the following code:

override func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
    switch viewControllerCanEdit {
    case .viewControllerThatCanNotEdit:
        return false
    default:
        tableView.cellForRow(at: indexPath)?.reuseIdentifier == "CellThatAllowsEditing" else { return false }
        return true
    }
}

I'm getting the following Assertion Error:

[Assert] Attempted to call -cellForRowAtIndexPath: on the table view while it was in the process of updating its visible cells, which is not allowed. Make a symbolic breakpoint at UITableViewAlertForCellForRowAtIndexPathAccessDuringUpdate to catch this in the debugger and see what caused this to occur. Perhaps you are trying to ask the table view for a cell from inside a table view callback about a specific row? Table view: <UITableView: 0x7fd48303ec00; frame = (0 0; 414 896); clipsToBounds = YES; autoresize = W+H; gestureRecognizers = <NSArray: 0x60000284e070>; layer = <CALayer: 0x60000264f340>; contentOffset: {0, -100}; contentSize: {414, 2765.3333333333335}; adjustedContentInset: {100, 0, 83, 0}; dataSource: <TableViewController: 0x7fd48281b000>>

I've narrowed down the cause. Supposedly this error is a result of the tableView calling canEditRowAt() while it's in the process of updating the data. And because of that, the call to match the tableView.cellForRow(at:) doesn't yet exist.

My question is; Is there a way to break out of the function if the tableView is updating? Or if there is a better way of trying to match if the cell can be edited based on the cells type?

vadian vadian · Accepted Answer · 2020-09-11T18:42:35

A better way is to add a property in the data model

var canEdit = false

maintain it and check it (dataSourceArray is the data source array)

override func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
    switch viewControllerCanEdit {
    case .viewControllerThatCanNotEdit:
        return false
    default:
        return dataSourceArray[indexPath.row].canEdit
    }
}

Swift - TableView Assert Error: cellForRowAtIndexPath Because of: canEditRowAt()

1 Answers