Adding a footer to NSTableView

NSTableViewFooter.swift

import Cocoa

class TableContainerView : NSView {
    let tableView : NSTableView
    let footerView : NSView
    
    init(tableView: NSTableView) {
        self.tableView = tableView
        
        var containerFrame = tableView.frame
        containerFrame.size.height = containerFrame.size.height + 30
        tableView.frame.origin.y = 30
        
        footerView = NSTextField(labelWithString: "Footer")
        footerView.frame.origin.y = 5
        
        super.init(frame: containerFrame)
        addSubview(footerView)
        addSubview(tableView)
        
        if let scrollView = tableView.enclosingScrollView,
           let documentView = scrollView.documentView {
            scrollView.scroll(NSPoint(x: 0, y: documentView.bounds.size.height))
        }
    }
    
    // NSTableView checks if its enclosing scrollview's documentView has a headerView method
    // and won't draw it if it doesn't.
    @objc open var headerView: NSTableHeaderView? {
        return tableView.headerView
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

class ViewController: NSViewController {
    @IBOutlet var tableView : NSTableView!
    
    override func viewDidLoad() {
        super.viewDidLoad()

        let scrollView = tableView.enclosingScrollView!
        scrollView.documentView = TableContainerView(tableView: tableView)
    }
}