UITableView with transparent cells overlap old cells when reloading data

Question

I have a UITableView with a transparent background color and cells which also have a transparent background color. When I reload my tableView with:

dataSource = some new data
tableView.reloadData()

I can see the new cells overlap the old ones.

I did try to use use

tableView.beginUpdates()
// remove all rows here
change data source
// insert new rows here
tableView.endUpdates()

but it did not work. I tried as well tableView.reloadRowsAtIndexPath(...) but still no luck.

And finally I set all my cells and my table view to clear graphic context when redrawn but it did not manage to fix this issue.

Any help would be greatly appreciated.

---

My cell creation function:

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("suggestioncell")
    cell.backgroundColor = UIColor.whiteColor().alpha(0.1)
    cell.textLabel?.text = (suggestions![indexPath.row] as! SVPlacemark).formattedAddress
    cell.clearsContextBeforeDrawing = true
    cell.contentView.clearsContextBeforeDrawing = true
    return cell
}

Answer 1

Try overriding prepareForReuse in you UITableViewCell subclass, and reset content there.

Here's what the documentation says about that:

Prepares a reusable cell for reuse by the table view's delegate.

If a UITableViewCell object is reusable—that is, it has a reuse identifier—this method is invoked just before the object is returned from the UITableView method dequeueReusableCellWithIdentifier:. For performance reasons, you should only reset attributes of the cell that are not related to content, for example, alpha, editing, and selection state. The table view's delegate in tableView:cellForRowAtIndexPath: should always reset all content when reusing a cell. If the cell object does not have an associated reuse identifier, this method is not called. If you override this method, you must be sure to invoke the superclass implementation.

Answer 2

Custom UITableViewCell class:

class customCell: UITableViewCell {
    override func prepareForReuse() {
        self.textLabel?.text = nil
    }
}

In your cellForRowAtIndexPath method:

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("suggestionCell", forIndexPath: indexPath) as! customCell
    cell.backgroundColor = UIColor.whiteColor().alpha(0.1)
    cell.textLabel?.text = (suggestions![indexPath.row] as! SVPlacemark).formattedAddress
    return cell
}

And, of course in your XIB/Storyboard, set the cell class to CustomCell, and set its reuse identifier.