Probable Bug in tableview - ios

Question

I have a UITablViewController and implementing the following :
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
[self.tableView cellForRowAtIndexPath:self.oldIndexPath].accessoryType = UITableViewCellAccessoryNone;
NSLog(#"%#", indexPath);
UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:indexPath];
cell.accessoryType = UITableViewCellAccessoryCheckmark;
self.oldIndexPath = indexPath;
}
What I notice is, the checkmark appears on 2 cells, one with index path, for example, if I select a cell with index path {length = 2, path = 0 - 2} and scrolling down I notice the checkmark is also visible on {length = 2, path = 0 - 14}
There is just 1 section in the table view and around 18-19 rows.
Can somebody verify this for me / or is it time for me to get some sleep :/ ?
P.S : tested this on simulator and device
The cells are created as follows :
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
// Configure the cell...
cell.textLabel.text = self.stationsDictionary[#"urls"][indexPath.row][#"title"];
return cell;
}

Answer 1

Since your cells are reusable (I suppose), you need to set this in
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
[self.tableView cellForRowAtIndexPath:self.oldIndexPath].accessoryType = UITableViewCellAccessoryNone;
NSLog(#"%#", indexPath);
self.oldIndexPath = indexPath;
for (UITableViewCell *cell in tableView.visibleCells) {
if ([tableView indexPathForCell:cell].section == indexPath.section && [tableView indexPathForCell:cell].row == indexPath.row) {
cell.accessoryType = UITableViewCellAccessoryCheckmark;
}
}
}
and
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
// Configure the cell...
cell.textLabel.text = self.stationsDictionary[#"urls"][indexPath.row][#"title"]; return cell;
cell.accessoryType = self.oldIndexPath.section == indexPath.section && self.oldIndexPath.row == indexPath.row ? UITableViewCellAccessoryCheckmark : UITableViewCellAccessoryNone;
}
Or the reused cell will keep the state of the previous cell (the one reused) which can be checked.
Common error ;)

Answer 2

When you dequeue a cell from cellForRowAtIndexPath, be sure to reset its status - in your case, the accessoryType property.
Since cells are reused, what happens is that when cell with index 2 is not visible, it is reused to display row with index 14.
As a consequence of that, you need to save each cell state if you want to preserve its status (in your case in didSelectRowAtIndexPath if you only need to save the accessoryType property), and restore into the cell in cellForRowAtIndexPath.
You can use an NSArray, using the cell index as array index, to save your cell status, or even a "normal" array of UITableViewCellAccessoryType or booleans