UISwitch resets when scrolling up and down - ios

Question

I have a question about the event value changed for UISwitch, here is my problem in detail.
in numberOfRowsInSection i have loop that calls the a data base method which return #of rows for each section.
I used an array of arrays(BECAUSE OF I HAVE MANY SECTIONS WITH MANY ROWS) that keeps state of UISwitch then update it whenever value changed called, here is the code of the event:
HOWEVER, after all of these UISwitch still resets whenever I scroll up or down. PLEASE HELP ME AS SOON AS POSSIBLE I will appreciate YOUR HELP SOOOOO MUCH .
Thank you in advance.

Answer 1

I think you make logic error in if (sender.on) in -(void)switchChanged:(UISwitch *)sender method because when sender.on == YES you make OFF:) write
-(void)switchChanged:(UISwitch *)sender
{
UITableViewCell *cell = (UITableViewCell *)[sender superview];
NSIndexPath *x =[mainTableView indexPathForCell:cell];
NSMutableArray *repl = [SwitchArray objectAtIndex:x.section];
[repl replaceObjectAtIndex:x.row withObject:(sender.on ? #"ON", #"OFF")];
}

Answer 2

You can double check the value in the table view willDisplayCell: just to make sure you have it right:
- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
UISwitch* uiSwitch = (UISwitch*) cell.accessoryView;
if (uiSwitch != nil && [uiSwitch isKindOfClass:[UISwitch class]]) {
//just make sure it is valid
NSLog(#"switch value at %d-%d is: %#",indexPath.section, indexPath.row, [SwitchArray[indexPath.section] objectAtIndex:indexPath.row] );
uiSwitch.on = [[SwitchArray[indexPath.section] objectAtIndex:indexPath.row] isEqualToString:#"ON"];
}
}
As an aside, you can you use NSNumbers to make the code more readable:
-(void)switchChanged:(UISwitch *)sender
{
UITableViewCell *cell = (UITableViewCell *)[sender superview];
NSIndexPath *x=[mainTableView indexPathForCell:cell];
NSLog(#"%ld", (long)x.section);
//NSLog(#"index for switch : %d", switchController.tag );
NSMutableArray *repl = repl= [SwitchArray objectAtIndex:x.section];
repl[x.section] = #(sender.on);
}
Then where you set the on value:
uiSwitch.on = [[SwitchArray[indexPath.section] objectAtIndex:indexPath.row] boolValue];

Answer 3

Cells get reused. You are creating a new switch every time a cell is used. You should only create a switch once for each cell. Try the following in your cellForRow... method:
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:CellIdentifier];
UISwitch *switchController = [[UISwitch alloc] initWithFrame:CGRectZero];
[switchController setOn:YES animated:NO];
[switchController addTarget:self action:#selector(switchChanged:) forControlEvents:UIControlEventValueChanged];
cell.accessoryView = switchController;
[switchController release];
}
UISwitch *switch = cell.accessoryView;