防止所选单元被重用

Question

So I have a tableview that has a list of items in each cell. Each of these cells contain an image view which, upon being tapped, expands the cell and displays the image for that item. When I scroll down the table view and scroll back up to the cell that was selected, the image is gone. I know this is due to reusing cells but I'm not sure on how to keep the expanded cells image in place while scrolling through other items.

The closest I've come is here: my table view reuse the selected cells when scroll -- in SWIFT

If someone could lend me a hand that would be awesome. Thanks!

Edit: Adding code snippets - Sorry for the wait.

fileprivate var expandedRowIndex: Int?

// cellForRowAt
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
{
    // CatalogItem row.
    let item = self.items[indexPath.row]
    let expanded = indexPath.row == self.expandedItemRowIndex

    // Return standard catalog item cell.
    let reuseID = expanded
                ? CatalogItemCell.PROTOCELL_EXPANDED.id
                : CatalogItemCell.PROTOCELL.id
    let cell = tableView.dequeueReusableCell(withIdentifier: reuseID) as! CatalogItemCell

    // Reset thumbnail image back to nil. Needed so that images appear
    // only in the cell that they belong in.
    if indexPath.row == self.expandedRowIndex{
        cell.uiImage_Thumbnail.image = nil
    }       
    return cell
}

// didSelectRowAt
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath)
{
    tableView.deselectRow(at: indexPath as IndexPath, animated: true)

    // Expand row - Get the current cell and show image
    self.expandedItemRowIndex = indexPath.row
    let item = self.items[indexPath.row]
    let currentCell = tableView.cellForRow(at: indexPath)

    // Pass both the selected cell and item to the ImageManager
    ImageManager.startImageRequest(currentCell: currentCell!, item: item)

    if self.expandedRowIndex == indexPath.row
    {
       // Selected row is already expanded.
       return
    }

    var reloadPaths = [IndexPath]()

    // Collapse previously expanded row.
    if let previousRowIndex = self.expandedRowIndex
    {
        reloadPaths.append(IndexPath(row: previousRowIndex, section: 0))
    }

    // Expand the selected row.
    self.expandedRowIndex = indexPath.row
    let item = self.items[indexPath.row]
    debugPrint(item.description)
    reloadPaths.append(IndexPath(row: indexPath.row, section: 0))
    tableView.reloadRows(at: reloadPaths as [IndexPath], with: .fade)

}

Answer 1

You can maintain a selectedIndex variable. In your cellForRow you check whether this call is for selectedCell. If yes, then do the customisation that is required for selected cell.

Also you might want to handle heightForRow, there also check whether the call is for selected cell.

You can maintain an indexPath for selected cell. If there are multiple sections. No need to prevent it from getting reused.

Hope that helps.