Removing all Sublayers from UitableViewCell - swift

Question

I have UITableView with 2 expanded Sections.
So, when I click on section's header, rows will be hidden:
override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
print("Section: \(indexPath.section), Row \(indexPath.row), \(sections[indexPath.section].expanded)")
if sections[indexPath.section].expanded {
return 88
} else {
return 0
}
}
I am adding an UIlabel to a cell in UITableView as below:
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath)
let label = UILabel()
cell.contentView.addSubview(label)
label.translatesAutoresizingMaskIntoConstraints = false
label.leftAnchor.constraint(equalTo: cell.leftAnchor).isActive = true
label.topAnchor.constraint(equalTo: cell.topAnchor).isActive = true
label.widthAnchor.constraint(equalTo: cell.widthAnchor).isActive = true
label.heightAnchor.constraint(equalToConstant: 30).isActive = true
label.text = "row = \(indexPath.row)"
return cell
}
The above is working but cells are not properly showing the screen as sometime, the content of row1 is printed in another row.
If I add the below code, and when I click on a header of any section, the rows will be properly showing on the tableView, but just one time, I mean if I click one more time on the header, an error occurs inside CellForRowAt function (Thread 1: EXC_BAD_ACCESS (code=EXC_I386_GPFLT)):
cell.contentView.layer.sublayers?.forEach { $0.removeFromSuperlayer() }
Any advise?
EDIT:
just to explain how the sections are expanded, i will add the following:
protocol ExpandableHeaderViewDelegate {
func toggleSection(header: ExpandableHeaderView, section: Int)
}
class ExpandableHeaderView: UITableViewHeaderFooterView {
var delegate: ExpandableHeaderViewDelegate?
var section: Int!
override init(reuseIdentifier: String?) {
super.init(reuseIdentifier: reuseIdentifier)
self.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(selectHeaderAction)))
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
#objc func selectHeaderAction(gestureRecognizer: UITapGestureRecognizer) {
let cell = gestureRecognizer.view as! ExpandableHeaderView
delegate?.toggleSection(header: self, section: cell.section)
}
func toggleSection(header: ExpandableHeaderView, section: Int) {
tableView.beginUpdates()
tableView.endUpdates()
}
}

Answer 1

My question was solved by [Knight0fDragon].
extension UIView
{
func clearSubviews()
{
for subview in self.subviews as! [UIView] {
subview.removeFromSuperview();
}
}
}
and then
cell.contentView.clearSubviews()
Thanks for all kind people for their support.

Answer 2

If the problem is just for mismatch of cell data then try using
override func prepareForReuse() {
super.prepareForReuse()
self.label.text = ""
}
Declare the UILabel in the cell's class with null value instead of declaring it in cellForRowAt

Answer 3

Try this inside cellForRowAt:
if tableView.rectForRow(at: indexPath).height == 0.0 {
return UITableViewCell()
}
It should be above all other code.

Answer 4

Try (call it before adding new label)
cell.contentView.subviews.removeAll()
instead of
cell.contentView.layer.sublayers?.forEach { $0.removeFromSuperlayer() }