Show/hide table view cell using UISwitch - swift

Question

I want to use UISwitch to show/hide a tableViewCell in a dynamic table view.
UISwitch is defined in a class of `UITableViewCell.
#IBOutlet weak var switchState: UISwitch!
And in the another file I want say if this switch is ON, the number of rows will be 5 otherwise it should be 4
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
let test = PopupViewCell()
if test.switchState?.isOn == true {
detailsTableView.reloadData()
return 5
} else {
return 4
}
}
But it's not working, and it always read `return 4.
I also test it:
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
let test = PopupViewCell()
if test.switchState.isOn {
detailsTableView.reloadData()
return 5
} else {
return 4
}
}
But I will get this error:
Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value
I am not sure that I have to use some action function before this process or not, I will be appreciated if someone can help me on that.

Answer 1

The most beginner friendly way to do it is with a delegate. When the Switch cell detects a .valueChanged event it should forward this to the delegate. The delegate in turn updates its model of whether or not to show the switch and then reloads the tableView.
Here is a Playground example:
import UIKit
import PlaygroundSupport
protocol SwitchDelegate: class {
func toggle(isOn: Bool)
}
class SwitchCell: UITableViewCell {
private lazy var switchControl: UISwitch = {
let switchControl = UISwitch()
contentView.addSubview(switchControl)
switchControl.translatesAutoresizingMaskIntoConstraints = false
switchControl.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 12).isActive = true
switchControl.centerYAnchor.constraint(equalTo: contentView.centerYAnchor).isActive = true
switchControl.addTarget(self, action: #selector(toggleSwitch(_:)), for: .valueChanged)
return switchControl
}()
private weak var delegate: SwitchDelegate?
override func awakeFromNib() {
super.awakeFromNib()
}
func configure(isOn: Bool, delegate: SwitchDelegate) {
switchControl.isOn = isOn
self.delegate = delegate
}
#objc private func toggleSwitch(_ sender: UISwitch) {
delegate?.toggle(isOn: sender.isOn)
}
}
class ViewController: UITableViewController {
private let data = (0..<5).map { $0 + 1 }
private var isOn = true
override func viewDidLoad() {
super.viewDidLoad()
tableView.register(UITableViewCell.self, forCellReuseIdentifier: String(describing: UITableViewCell.self))
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return data.count + (isOn ? 1 : 0)
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if isOn && indexPath.row == 0 {
let switchCell = SwitchCell(style: .default, reuseIdentifier: String(describing: SwitchCell.self))
switchCell.configure(isOn: isOn, delegate: self)
return switchCell
} else {
let cell = tableView.dequeueReusableCell(withIdentifier: String(describing: UITableViewCell.self), for: indexPath)
let dataIndex = indexPath.row - (isOn ? 1 : 0)
cell.textLabel?.text = String(describing: data[dataIndex])
return cell
}
}
}
extension ViewController: SwitchDelegate {
func toggle(isOn: Bool) {
self.isOn = isOn
tableView.reloadData()
}
}
PlaygroundPage.current.liveView = ViewController()