Setting a default child table view controller for segmented control - ios

Question

I can use the segmented control to switch between child table view controllers within a container view, but it doesn't show the cells of the first table view controller when I enter the scene for some reason. I have my segment index defaulted at 0, so it shows the highlight on the first segment, but it does not correspondingly show the cells.
Here is the code for the segmentedControl and container view:
import UIKit
class BarMainViewController: UIViewController {
let barSegmentedControl: UISegmentedControl = {
let barItems = ["Newest", "Rewarding", "Saved"]
let segmentedControl = UISegmentedControl(items: barItems)
segmentedControl.selectedSegmentIndex = 0
segmentedControl.addTarget(self, action: #selector(selectionDidChange(_:)), for: .valueChanged)
return segmentedControl
}()
let containerView: UIView = {
let view = UIView()
view.translatesAutoresizingMaskIntoConstraints = false
return view
}()
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(barSegmentedControl)
view.addSubview(containerView)
setDefaultVC()
barSegmentedControl.addUnderlineForSelectedSegment()
containerView.topAnchor.constraint(equalTo: barSegmentedControl.bottomAnchor).isActive = true
containerView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -49).isActive = true
containerView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
containerView.widthAnchor.constraint(equalTo: view.widthAnchor).isActive = true
}
#objc func selectionDidChange(_ sender: UISegmentedControl) {
updateView()
barSegmentedControl.changeUnderlinePosition()
}
private func updateView() {
if barSegmentedControl.selectedSegmentIndex == 0 {
remove(asChildViewController: BarRewardingViewController())
remove(asChildViewController: BarSavedViewController())
add(asChildViewController: BarNewestViewController())
} else if barSegmentedControl.selectedSegmentIndex == 1 {
remove(asChildViewController: BarNewestViewController())
remove(asChildViewController: BarSavedViewController())
add(asChildViewController: BarRewardingViewController())
} else {
remove(asChildViewController: BarNewestViewController())
remove(asChildViewController: BarRewardingViewController())
add(asChildViewController: BarSavedViewController())
}
}
private func add(asChildViewController viewController: UITableViewController) {
// Add Child View Controller
addChildViewController(viewController)
// Add Child View as Subview
containerView.addSubview(viewController.view)
// Configure Child View
viewController.view.translatesAutoresizingMaskIntoConstraints = false
// Notify Child View Controller
viewController.didMove(toParentViewController: self)
}
private func remove(asChildViewController viewController: UITableViewController) {
// Notify Child View Controller
viewController.willMove(toParentViewController: nil)
// Remove Child View From Superview
viewController.view.removeFromSuperview()
// Notify Child View Controller
viewController.removeFromParentViewController()
}
private func setDefaultVC() {
containerView.addSubview(BarNewestViewController().view)
}
}
And here is the code for the table view controller:
import UIKit
class BarNewestViewController: UITableViewController {
override func viewDidLoad() {
tableView.register(serviceCell.self, forCellReuseIdentifier: "service")
super.viewDidLoad()
view.backgroundColor = mainBlue
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 5
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
return tableView.dequeueReusableCell(withIdentifier: "service", for: indexPath)
}
}
class serviceCell: UITableViewCell {
override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
super.init(style: style, reuseIdentifier: reuseIdentifier)
setupViews()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
let nameLabel: UILabel = {
let label = UILabel()
label.text = "NAME"
label.font = UIFont(name: "Avnier-Heavy", size: 20)
label.translatesAutoresizingMaskIntoConstraints = false
return label
}()
func setupViews() {
addSubview(nameLabel)
backgroundColor = lightBlue
nameLabel.topAnchor.constraint(equalTo: topAnchor).isActive = true
nameLabel.leftAnchor.constraint(equalTo: leftAnchor).isActive = true
}
}

Answer 1

Because BarNewestViewController subclasses UITableViewController it automatically follows the UITableViewDataSource and UITableViewDelegate protocols e.g. tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int. It does NOT however tell the property tableView that comes with UITableViewController that it's delegate and dataSource is BarNewestViewController.
tableView.dataSource = self
tableView.delegate = self