WTF: Crashing NSTableHeaderCell subclass ¯\_(ツ)_/¯

AppDelegate.swift

//
//  AppDelegate.swift
//  TableZombies
//
//  Created by Christian Tietze on 18/05/16.
//  Copyright © 2016 Christian Tietze. All rights reserved.
//

import Cocoa

@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {

    @IBOutlet weak var window: NSWindow!

    @IBOutlet var tableVC: TableViewController!
}

let first = ["1", "2"]
let second = ["a", "b", "c", "d", "e", "f", "g"]

class TableViewController: NSViewController, NSTableViewDelegate, NSTableViewDataSource {

    var model = 1

    @IBOutlet var button: NSButton!
    var tableView: NSTableView! { return self.view as? NSTableView }

    var tableDidLoad = false

    override func awakeFromNib() {
        super.awakeFromNib()

        guard !tableDidLoad else { return }
        tableDidLoad = true
        removeAllColumns()
        switchTable(self)
    }

    func removeAllColumns() {
        tableView.tableColumns.forEach(tableView.removeTableColumn)
    }

    @IBAction func switchTable(sender: AnyObject) {

        self.model = model == 1 ? 2 : 1
        replaceTable()
    }

    func replaceTable() {

        let currentModel = [first, second][model-1]

        removeAllColumns()

        let content = "anything"
        let columns: [NSTableColumn] = currentModel.enumerate().map { index, columnContent in

            let column = NSTableColumn()
            let headerCell = TableHeaderCell()
            headerCell.content = "\(content)" // <-- this breaks it! Replace it with const value and everything's fine o_O
            column.headerCell = headerCell
            column.title = columnContent
            return column
        }

        columns.forEach(tableView.addTableColumn)
    }
}

class TableHeaderCell: NSTableHeaderCell {

    var content: String!
}