Cell Row multiple selection - iphone

Question

I have more than 50 rows in my tableView. If i have to view the 50th cell, i will have to scroll down. I have also enabled multiple Selections to my table. The problem is that when i select like 5 rows, and then scroll down i get some other rows also selected (rows which i didn't select, and was auto selected when i scrolled further below).
1.) How do i overcome this ?
My cellForRowAtIndexPath method
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
cell.textLabel.text=#"Text values";
}
My didSelectRowAtIndexPath method
UITableViewCell *cell = [self.tble cellForRowAtIndexPath:indexPath];
if ([cell accessoryType] == UITableViewCellAccessoryNone) {
[cell setAccessoryType:UITableViewCellAccessoryCheckmark];
}
else {
[cell setAccessoryType:UITableViewCellAccessoryNone];
}
2.) I am not sure if my didSelectRowAtIndexPath works correctly (as in allow multiple row selection ) Can someone help me solve this

Answer 1

You are storing the selection by setting the cell accessory view. When you reuse a selected cell, the accessory view is not reset. You need to set or unset the accessory view in cellForRowAtIndexPath as well (set if the index path is part of the table view's selection (indexPathsForSelectedRows), unset if not).
You may also find it helpful to store the selected state as part of your data model, so you can toggle easily in the didSelect... and also know what accessory view to display in cellForRow...

Answer 2

Your problem is that since you are reusing cells, the cells will show checkmarks if you dont "clean" them up... What you can do is keep some array to keep track of which cells are checked, initialized initally to whatever it is you want them to be, then in cell for row at index path you need to either set the cell as checked or not... for example
the didSelectRowAtIndexPath can look like
if ([cell accessoryType] == UITableViewCellAccessoryNone) {
[cell setAccessoryType:UITableViewCellAccessoryCheckmark];
[_array insertObject:[NSNumber numberWithInt:1] atIndex:indexPath.row];
}
else {
[cell setAccessoryType:UITableViewCellAccessoryNone];
[_array insertObject:[NSNumber numberWithInt:0] atIndex:indexPath.row];
}
then in cellForRowAtIndexPath you can do
BOOL checked=[[_array objectAtIndex:indexPath.row] boolValue];
if(checked)
{
[cell setAccessoryType:UITableViewCellAccessoryCheckmark];
}
else
{
[cell setAccessoryType:UITableViewCellAccessoryNone];
}
hope it helps