Question

I’m working on an iOS 5 project and I’m using a table view to select items that will be added in a set.
I correctly set AllowsMultipleSelectionDuringEditing to YES to have the bullets on left side and the contentView indented.

Now, my problem is that I have a list of pre-selected items that the user should see when entering in edit mode. I looked inside the documentation, but I didn’t find anything about it, for a way to preselect a list of index paths when entering in edit mode with multiple selection enabled. Is there a way provided by Apple to pre-select a certain number of items or should I develop this feature by myself?

Answer 1

Ok, I found out how to do it and a good and elegant way, it was simpler than excepted:

UITableView has the method selectRowAtIndexPath:animated:scrollPosition: that select a row.
The best way to accomplish what I was looking for is to create an NSSet of NSIndexPaths and, immediately after setting the UITableView in editing mode, iterate the set and select the cell one-by-one.

For example in this way:

- (NSArray *)_preselectedIndexPaths 
{
    NSMutableSet *preselectedItems = [NSMutableSet set];
    NSUInteger s = 0, r = 0;
    for (NSArray *section in self.data) {
        for (id item in section) {
            if ([item shouldBePreselected]) { //this is the condition
                [preselectedItems addObject:[NSIndexPath indexPathForRow:r inSection:s]];
            }
            r++;
        }
        s++;
    }

    return [preselectedItems allObjects];
}

and then, for select the items int the table view:

[self.tableView setEditing:![self.tableView isEditing] animated:YES];

for (NSIndexPath *ip in [self _preselectedIndexPaths]) 
    {
       [self.tableView selectRowAtIndexPath:ip 
                                   animated:YES 
                             scrollPosition:UITableViewScrollPositionNone];
    }

I hope this may help someone else.