Logic for UITableViewCellAccessoryCheckmark - iphone

Question

I want to make a typical situation: when user selects any cell, it's accessoryType turns in checkmark. Only one cell's accessoryType can be checkmark. And then I wanna save in NSUserDefaults indexPath.row so my app will be able to know which cell user selected and make some changes in options. So I wrote this wrong code:
didSelectRowAtIndexPath
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
// checkedIndexPath is NSIndexPath
if(self.checkedIndexPath)
{
UITableViewCell* uncheckCell = [tableView
cellForRowAtIndexPath:self.checkedIndexPath];
uncheckCell.accessoryType = UITableViewCellAccessoryNone;
}
UITableViewCell* cell = [tableView cellForRowAtIndexPath:indexPath];
cell.accessoryType = UITableViewCellAccessoryCheckmark;
self.checkedIndexPath = indexPath;
[[NSUserDefaults standardUserDefaults]setObject:[NSNumber numberWithInt:self.checkedIndexPath.row]forKey:#"indexpathrow" ];
}
cellForRowAtIndexPath
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
// Part of code from cellForRowAtIndexPath
if(indexPath.row == [[[NSUserDefaults standardUserDefaults]objectForKey:#"indexpathrow"]intValue ])
{
cell.accessoryType = UITableViewCellAccessoryCheckmark;
}
else
{
cell.accessoryType = UITableViewCellAccessoryNone;
}
return cell;
}
However, this code works badly. When you open the UITableView, there is an already selected cell in the table and when you press another there are two checkmarked cells...How can I improve my code or should I change it whole ? Any suggestions ?
Thanks !

Answer 1

Try this code:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
// checkedIndexPath is NSIndexPath
NSIndexPath *previousSelection = self.checkedIndexPath;
NSArray *array = nil;
if (nil != previousSelection) {
array = [NSArray arrayWithObjects:previousSelection, indexPath, nil];
} else {
array = [NSArray arrayWithObject:indexPath];
}
self.checkedIndexPath = indexPath;
[tableView reloadRowsAtIndexPaths:array withRowAnimation: UITableViewRowAnimationNone];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
// Part of code from cellForRowAtIndexPath
NSString *cellID = #"CellID";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellID];
if (nil == cell) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellID];
[cell autorelease];
}
// some code for initializing cell content
cell.selectionStyle = UITableViewCellSelectionStyleNone;
if(self.checkedIndexPath != nil && indexPath.row == self.checkedIndexPath.row)
{
cell.accessoryType = UITableViewCellAccessoryCheckmark;
} else {
cell.accessoryType = UITableViewCellAccessoryNone;
}
return cell;
}