//Not preferred:
class MyViewController: UIViewController, UITableViewDataSource, UIScrollViewDelegate {
// all methods
}
//Preferred:
class MyViewController: UIViewController {
// class stuff here
}

// MARK: - UITableViewDataSource
extension MyViewController: UITableViewDataSource {
// table view data source methods
}

// MARK: - UIScrollViewDelegate
extension MyViewController: UIScrollViewDelegate {
// scroll view delegate methods
}