UITableViewCell has incorrect change on indexPath - ios

Question

I try to use UITableViewCell's accessoryType property to checkmark cell when clicked ,but when cell selected , the checkmark set several time for different cells for example when I select row [0] , row [0] and row [8] and row [17] AccessoryType set to checkmark !
public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "npCell", for: indexPath) as! NewPlaylistTableViewCell
cell.mTitle.text = musics[indexPath.row]["title"] as! String?
cell.mArtist.text = musics[indexPath.row]["artist"] as! String?
cell.selectionStyle = .none
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let cell = tableView.cellForRow(at: indexPath)
cell?.accessoryType = .checkmark
tableView.reloadData()
}

Answer 1

For single selection, you need to track your selected indexPath in a viewController variable,
var selectedIndexPath : IndexPath?
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
self.selectedIndexPath = indexPath
tableView.reloadData()
}
public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "npCell", for: indexPath) as! NewPlaylistTableViewCell
cell.mTitle.text = musics[indexPath.row]["title"] as! String?
cell.mArtist.text = musics[indexPath.row]["artist"] as! String?
cell.accessoryType = .none
cell.selectionStyle = .none
if(indexPath == selectedIndexPath) {
cell.accessoryType = .checkmark
}
return cell
}
Even better (avoiding reload the entire UITableView)
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let previousSelectedIndexPath = self.selectedIndexPath
self.selectedIndexPath = indexPath
if(previousSelectedIndexPath != nil) {
self.tableView.reloadRows(at: [previousSelectedIndexPath!,self.selectedIndexPath!], with: .automatic)
}else{
self.tableView.reloadRows(at: [self.selectedIndexPath!], with: .automatic)
}
self.tableView.reloadData()
}
UPDATE, Allowing multiple selection
For multiple selection you should track selected cells in a Dictionary for convenience faster access to selected and unselected indexPaths allowing you use multiple sections because the key value of our Dictionary is a string formed by (IndexPath.section)+(IndexPath.row) which is always unique combination
var selectedIndexPaths : [String:Bool] = [:]
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let currentIndexPathStr = "\(indexPath.section)\(indexPath.row)"
if(self.selectedIndexPaths[currentIndexPathStr] == nil || !self.selectedIndexPaths[currentIndexPathStr]!) {
self.selectedIndexPaths[currentIndexPathStr] = true
}else{
self.selectedIndexPaths[currentIndexPathStr] = false
}
self.tableView.reloadRows(at: [indexPath], with: .automatic)
}
public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "npCell", for: indexPath) as! NewPlaylistTableViewCell
cell.mTitle.text = musics[indexPath.row]["title"] as! String?
cell.mArtist.text = musics[indexPath.row]["artist"] as! String?
cell.accessoryType = .checkmark
let currentIndexPathStr = "\(indexPath.section)\(indexPath.row)"
if(self.selectedIndexPaths[currentIndexPathStr] == nil || !self.selectedIndexPaths[currentIndexPathStr]!) {
cell.accessoryType = .none
}
return cell
}
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