How to enable a button if one or more checkbox is selected

EnableButtonIfAtLeastOneCheckboxIsSelected.swift

//
//  EnableButtonIfAtLeastOneCheckboxIsSelected.swift
//  SplashBuddy
//
//  Created by François Levaux on 23.05.17 (Swift 3)
//  Copyright © 2017 François Levaux-Tiffreau. All rights reserved.
// 
// Create 5 checkboxes & link them to this file
// Create one button, bind "Enabled" to "Enable Button If At Least One Checkbox Is Selected" 
// with Model Key Path set to "self.atLeastOneSelectedButton"
//
// tl;dr use "directory1Button.cell.state"

import Cocoa

class EnableButtonIfAtLeastOneCheckboxIsSelected: NSViewController {

    @IBOutlet weak var directory1Button: NSButton!
    @IBOutlet weak var directory2Button: NSButton!
    @IBOutlet weak var directory3Button: NSButton!
    @IBOutlet weak var directory4Button: NSButton!
    @IBOutlet weak var directory5Button: NSButton!
    
  // Register Dependent Keys
  // https://developer.apple.com/library/content/documentation/Cocoa/Conceptual/KeyValueObserving/Articles/KVODependentKeys.html
    dynamic class func keyPathsForValuesAffectingAtLeastOneSelectedButton() -> Set<String> {
        return ["directory1Button.cell.state",
                "directory2Button.cell.state",
                "directory3Button.cell.state",
                "directory4Button.cell.state",
                "directory5Button.cell.state"]
    }
    
    dynamic var atLeastOneSelectedButton: Bool {
        return self.compileDirectoryButtons().contains(where: { $1 == true })
    }
    
    private func intToBool(_ int: Int) -> Bool {
        return int == NSOnState ? true : false
    }
    
    private dynamic func compileDirectoryButtons() -> Dictionary<String, Bool> {
        var result = Dictionary<String, Bool>()
        result["directory1"] = intToBool(self.directory1Button.state)
        result["directory2"] = intToBool(self.directory2Button.state)
        result["directory3"] = intToBool(self.directory3Button.state)
        result["directory4"] = intToBool(self.directory4Button.state)
        result["directory5"] = intToBool(self.directory5Button.state)
        return result
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
    }
}