How do I retrieve UITableView row number of a UISwitch?

Question

I have tried several approaches posted here, but I cannot get my table full of switches to return an index value for the cell of the changed switch. I am creating the view containing the table programmatically (no xib).

TableSandboxAppDelegate.m I instantiate the view controller in didFinishLaunchingWithOptions: with:

...
TableSandboxViewController *sandboxViewController = [[TableSandboxViewController alloc]
    init];
[[self window] setRootViewController:sandboxViewController];
...

TableViewController.h file reads:

@interface TableSandboxViewController : UITableViewController
{
   NSMutableArray *_questionOrder;
   NSMutableArray *switchStates;
}
@end

TableViewController.m cellForRowAtIndexPath: reads:

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"MainCell"];

UISwitch *theSwitch = nil;

if (cell == nil) {
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
        reuseIdentifier:@"MainCell"];

    theSwitch = [[UISwitch alloc] initWithFrame:CGRectZero];
    theSwitch.tag = 100;
    [theSwitch addTarget:self action:@selector(switchChanged:)   
        forControlEvents:UIControlEventValueChanged];
    [cell.contentView addSubview:theSwitch];

} else {
    theSwitch = [cell.contentView viewWithTag:100];
}

if ([[switchStates objectAtIndex:indexPath.row] isEqualToString:@"ON"]) {
    theSwitch.on = YES;
} else {
    theSwitch.on = NO;
}

return cell;

TableViewController.m -(IBAction)switchChanged:(UISwitch *)sender reads:

UITableViewCell *theParentCell = [[sender superview] superview];
NSIndexPath *indexPathOfSwitch = [self.tableView indexPathForCell:theParentCell];

NSLog(@"Switch changed at index: %d", indexPathOfSwitch.row);

My log result is always "Switch changed at index: 0". I feel like the problem is in that CGPoint line where I've tried combinations of replacements for "sender" ([sender superview], [[sender superview]superview], etc). I don't feel like that line is pointing to the view that displays the table.

What am I doing wrong?

Note added 10/9, 9:15 EDT: my goal is to be able to handle about 100 yes/no questions in the table, so reuse is a key. I want to scroll and have the table the state of each switch, as well as be able to retrieve them when leaving the view.

Answer 1

Tags is an okay solution, but a little clumsy because the cells - and therefore their subviews - are continually being reused, changing their rows - and therefore the tags they need.

Instead, I generally keep one of these around:

- (NSIndexPath *)indexPathWithSubview:(UIView *)subview {

    while (![subview isKindOfClass:[UITableViewCell self]] && subview) {
        subview = subview.superview;
    }
    return [self.tableView indexPathForCell:(UITableViewCell *)subview];
}

Then when I get an IBAction:

- (IBAction)someSubviewAction:(id)sender {

    NSIndexPath *indexPath = [self indexPathWithSubview:(UIView *)sender];
    // carry on from here
}

Answer 2

You may set switch view tag to row index. Instead of theSwitch.tag = 100;

do

-(UITableViewCell*)tableView:table cellForRowAtIndexPath:indexPth
{
    UISwitch *theSwitch = nil;
    if (cell == nil) {
        ...
        // as per your example
        [cell.contentView addSubview:theSwitch];
    } else {
        theSwitch = subviewWithClass(cell.contentView, [UISwitch class]);
    }

    theSwitch.tag = indexPath.row;
    ...
}

Add this helper function to replace viewWithTag: call

UIView *subviewWithClass(UIView *contentview, Class klass)
{
    for (UIView *view in contentview.subviews)
        if ([view isKindOfClass:klass])
            return view;
    return nil;
}

Then retrieve tag, that is a row index now, in your switchChanged function

-(IBAction)switchChanged:(UISwitch *)sender {
    NSLog(@"Selected Switch - %d", sender.tag);
    ...
 }