Do not add an existing item in the cellForRowAtIndexPath - ios

Question

In my TableViewController I use custom cell, this cell has a scrollView. My cellForRowAtIndexPath method looks like:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
CustomCell *cell = (CustomCell *)[tableView dequeueReusableCellWithIdentifier:#"cell"];
if (!cell) {
cell = [[CustomCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:#"cell"];
// iOS 7 separator
if ([cell respondsToSelector:#selector(setSeparatorInset:)]) {
cell.separatorInset = UIEdgeInsetsZero;
}
}
UIView *subview = [cell viewWithTag:indexPath.row + 1];
if (!subview) {
//... Set up the new cell
[self addScrollViewForCell:cell andCellIndx:indexPath.row];
}
else {
// ... Reuse the cell
}
return cell;
}
If view already exist - I'm trying do not add scrollView. If not - add.
addScrollViewForCell: method:
- (void)addScrollViewForCell: (CustomCell *)tCell andCellIndx:(NSInteger)cIndx {
UIScrollView * myScrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(5, 62, 350, 61)];
myScrollView.accessibilityActivationPoint = CGPointMake(100, 100);
//Some settings
// ...
UILabel *lblH = [[UILabel alloc] init];
lblH.textAlignment = NSTextAlignmentCenter;
lblH.text = strWeekIdntfr;
lblH.textColor = [UIColor blueColor];
lblH.frame = CGRectMake(offsetScores, 0, cCurrWeekBallsWidth, 15);
[myScrollView addSubview:lblH];
myScrollView.tag = cIndx + 1;
[tCell addSubview:myScrollView];
}
The problem is - when I scroll table to the bottom or to the up, scrollView begin to be added. Checking view by tag I try to differentiate reusable and new one cells, but this didn't work. How Can I solve this?

Answer 1

The reason is because an instance of UITableViewCell is reused when you scroll.
Each time it's being reused, this line UIView *subview = [cell viewWithTag:indexPath.row + 1]; will query for view with different tag. Say, you have 100 cells in this UITableView, a cell might be asked for tag 1, 6, 11, 16, 21 ... 96, which clearly it doesn't have. So it's likely to create a new view every time it's being reused. Multiply this with every cell in the pool and you will get hell load of new scroll views added to them.
To solve this: Just use a fix tag number.
So the line.
UIView *subview = [cell viewWithTag:indexPath.row + 1];
become:
UIView *subview = [cell viewWithTag:1];
And:
myScrollView.tag = cIndx + 1;
become:
myScrollView.tag = 1;
And as #AdamPro13 pointed out, a better and much more elegant way is that you create the scroll view as part of your custom cell. Just put it in initWithFrame:style: of the UITableViewCell's subclass.

Answer 2

The best way that I found it just clear all subview from scrollView. For example like that:
[myCell.scrollView.subviewsmakeObjectsPerformSelector:#selector(removeFromSuperview)];