Section Headers

// Using a UITableViewController

class SecHeadTVC: UITableViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        self.title = "Section Header TableViewController"

        tableView.register(UITableViewCell.self, forCellReuseIdentifier: "c")

        if #available(iOS 15.0, *) {
            tableView.sectionHeaderTopPadding = 0.0
        }

    }

    override func numberOfSections(in tableView: UITableView) -> Int {
        return 5
    }
    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return section + 1
    }
    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let c = tableView.dequeueReusableCell(withIdentifier: "c", for: indexPath)
        c.textLabel?.text = "\(indexPath)"
        c.textLabel?.backgroundColor = .cyan
        c.contentView.backgroundColor = .yellow
        return c
    }

    override func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
        let v = UILabel()
        v.text = "Header for section: \(section)"
        v.backgroundColor = .green
        return v
    }
}

// Using a UITableView as a Subview of a UIViewController

class SecHeadVC: UIViewController, UITableViewDataSource, UITableViewDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()

        self.title = "Section Header TableView as Subview"
        view.backgroundColor = .systemYellow

        let tv = UITableView()
        tv.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(tv)

        let g = view.safeAreaLayoutGuide

        NSLayoutConstraint.activate([

            tv.topAnchor.constraint(equalTo: g.topAnchor, constant: 20.0),
            tv.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
            tv.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
            tv.bottomAnchor.constraint(equalTo: g.bottomAnchor, constant: -20.0),

        ])

        tv.register(UITableViewCell.self, forCellReuseIdentifier: "c")
        tv.dataSource = self
        tv.delegate = self

        if #available(iOS 15.0, *) {
            tv.sectionHeaderTopPadding = 0.0
        }

    }

    func numberOfSections(in tableView: UITableView) -> Int {
        return 5
    }
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return section + 1
    }
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let c = tableView.dequeueReusableCell(withIdentifier: "c", for: indexPath)
        c.textLabel?.text = "\(indexPath)"
        c.textLabel?.backgroundColor = .cyan
        c.contentView.backgroundColor = .yellow
        return c
    }

    func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
        let v = UILabel()
        v.text = "Header for section: \(section)"
        v.backgroundColor = .green
        return v
    }
}