Uiswitch in uitableviewcell reset when scroll up or down? - ios

Question

I have a problem with my UISwitch inside a UITableViewCell. When I change the value of one switch then scroll up or down all switches are messed up. I use an array to store state for each switch due to reusability they are still messed up every time.
Here is cellForRowAtIndexPath method:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell"];
if (cell == nil)
{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:#"Cell"];
}
UISwitch *switchController = [[UISwitch alloc] initWithFrame:CGRectZero];
CGRect switchFrame = switchController.frame;
[switchController setOn:YES animated:NO];
//set its x and y value, this you will have to determine how to space it on the left side
switchFrame.origin.x = 50.0f;
switchFrame.origin.y = 10.0f;
switchController.frame = switchFrame;
[switchController addTarget:self action:#selector(switchChanged:) forControlEvents:UIControlEventValueChanged];
[cell addSubview:switchController ];
UILabel *label ;
label=(UILabel *)[cell viewWithTag:1];
NSString *value = [[mainArray objectAtIndex:indexPath.section] objectAtIndex:indexPath.row];
label.text = value;
label.textAlignment = NSTextAlignmentRight;
label.autoresizingMask = UIViewAutoresizingFlexibleRightMargin;
//This for persist switch state when scroll up or down
if ([[[self.SwitchArray objectAtIndex:indexPath.section] objectAtIndex:indexPath.row ]isEqualToString:#"ON"])
{
switchController.on=YES;
}
else
{
switchController.on=NO;
}
return cell;
}
Here is SwitchChanged event :
-(void)switchChanged:(UISwitch *)sender
{
UITableViewCell *cell = (UITableViewCell *)[[sender superview] superview];
NSIndexPath *index=[mainTableView indexPathForCell:cell];
if (sender.on)
{
[[self.SwitchArray objectAtIndex:index.section] replaceObjectAtIndex:index.row withObject:#"ON"];
NSString *word= [[self.mainArray objectAtIndex:index.section ] objectAtIndex:index.row];
}
else
{
//call the first array by section
[[self.SwitchArray objectAtIndex:index.section] replaceObjectAtIndex:index.row withObject:#"OFF"];
NSString *word= [[self.mainArray objectAtIndex:index.section ] objectAtIndex:index.row];
}
[padFactoids setObject:[NSKeyedArchiver archivedDataWithRootObject:SwitchArray] forKey:#"savedArray"];
[padFactoids synchronize];
}
I will appreciate your help so much.

Answer 1

In your header file declare an NSMutableArray, let's name it switchStates.
In your viewDidLoad, allocate memory and add object with the string "OFF" according to number of switches:
switchStates = [[NSMutableArray alloc] init];
for (int i; i <= switchesArray.count; i++) {
[switchStates addObject:#"OFF"];
}
In your method which runs when the switch is triggered:
NSString *theSwitchPosition = [NSString stringWithFormat:#"%#", switchControl.on ? #"ON" : #"OFF"];
[switchStates replaceObjectAtIndex:aPath.row withObject:theSwitchPosition];
After that, in the method where you create your switches:
if ([[switchStates objectAtIndex:indexPath.row] isEqualToString:#"ON"]) {
mySwitch.on = YES;
} else {
mySwitch.on = NO;
}
This worked for me, good luck..

Answer 2

I am not sure whether this causes your problem, but it will certainly cause other related problems.
Each time when a cell was moved off screen and a next one appears, the one that just moved off screen will be reused.
But you add a new switch object every time to the cell. You are far better off creating those only within the cell==nil block. Give it a tag and use the tag to fetch the object upon reusage as you do with the lable object.

Answer 3

You're creating a new switch every time the tableView is asking for a cell. You only want to create the switch once for each cell:
UISwitch *switchController;
if (cell == nil)
{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:#"Cell"];
switchController = [[UISwitch alloc] initWithFrame:CGRectZero];
CGRect switchFrame = switchController.frame;
[switchController setOn:YES animated:NO];
//set its x and y value, this you will have to determine how to space it on the left side
switchFrame.origin.x = 50.0f;
switchFrame.origin.y = 10.0f;
switchController.frame = switchFrame;
[switchController addTarget:self action:#selector(switchChanged:) forControlEvents:UIControlEventValueChanged];
[cell.contentView addSubview:switchController ];
switchController.tag = 123; //Arbitrary number...can be anything
}
else {
switchController = (UISwitch *)[cell.contentView viewWithTag:123];
}
//Now set the switch state according to your data model array
It's also generally a better practice to add subviews to the cell's contentView rather than the cell itself.