Sender sometimes send wrong value - ios

Question

I have UICollectionView with custom flow layout, which purpose is availability to delete items. In order to retrieve index i use function:
-(void)aMethod:(UIButton*)sender{
[self.viewModel deleteAt:[sender tag]];
[self.myCollectionView reloadData];
}
Sometimes (in rare cases) i got crash. When i dig into it, i found that sometimes [sender tag] was incorrect, in fact, higher then array of items count. Why is that happen? I found that it send 8, when array only had 5 items.
Button is simple 40x40 width/height image, placed above UITableViewCell like this:
UIButton *button = [UIButton new];
[button setImage:[UIImage imageNamed:#"m_delete"] forState:UIControlStateNormal];
if (self.shouldEdit){
self.layout.longPressGestureRecognizer.minimumPressDuration = 0.3f;
NSLog(#"1 blk called");
[button addTarget:self
action:#selector(aMethod:)
forControlEvents:UIControlEventTouchUpInside];
[button setTag:indexPath.row];
[cell addSubview:button];
[button mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.equalTo(cell.mas_left).with.offset(2);
make.top.equalTo(cell.mas_top).with.offset(2);
}];
}

Answer 1

I suspect that it's reusing old cell without updating the button's tag. Since you have conditions if (self.shouldEdit) which means the [button setTag:indexPath.row]; is not always called. You mentioned that the purpose of the buttons is to delete items so it might be that the tableView reused old / deleted cell (the one with tag 8) as one of the 5 cells and it doesn't call the setTag
You can take the setTag line outside the conditional so it will always update the button's tag every time the cell is created / reused.
Alternatively you can make sure the old button are removed from cell before reuse in UITableViewCell's prepareForReuse or inside cellForRowAtIndexPath right after dequeueReusableCellWithReuseIdentifier(...). Doing this you must always add new button because the old ones are removed from the cell

Answer 2

button tag is override every time when cellForRowAtIndexPath callled so dont set tag in that method
remove this line
[button setTag:indexPath.row];
use this one
-(void)aMethod:(UIButton*)sender
{
CGPoint point=[sender convertPoint:CGPointZero toView:collectiewname];
NSIndexPath *indexPath=[collectiewname indexPathForItemAtPoint:point];
NSLog(#"row :%ld",(long)indexPath.row)
}