How to pass a reference to a Boolean rather than its value?

Question

I want to use booleans as state storage.

In order to do that, I need to be able to change their state from difference places in the project.

To do that, I need somewhere to store them, and a way to pass a reference to them.

I've tried storing them as static variables in a GameManager, but passing references to these only seems to pass the value of true of false, not a reference.

How do I achieve this goal of having a passable boolean reference I can change the state of it from any part of the project?

UPDATE:

This can't be the best way to do this, but this achieves the goal of having a bunch of state booleans that I can use around the game world:

class GameManager {

    static let sharedInstance = GameManager()

    var previewAudioIsON: Bool = false
    var previewVisuaIsOn: Bool  = false
    var timerDisplayIsOn: Bool  = false
    var quickStartIsOn: Bool  = false

    func touchedPreviewAudioButton() -> Bool {
        if previewAudioIsON { previewAudioIsON = false}
        else { previewAudioIsON = true }
     return previewAudioIsON
    }

    func touchedPreviewVisualButton() -> Bool {
        if previewVisuaIsOn { previewVisuaIsOn = false }
        else { previewVisuaIsOn = true }
     return previewVisuaIsOn
    }

    func touchedTimeDisplayButton() -> Bool {
        if timerDisplayIsOn { timerDisplayIsOn = false }
        else { timerDisplayIsOn = true }
     return timerDisplayIsOn
    }

    func touchedQuickStartButton() -> Bool {
        if quickStartIsOn { quickStartIsOn = false }
        else { quickStartIsOn = true }
     return quickStartIsOn
    }
}

Answer 1

I gave you partially wrong information the other day ( I was having a brain fart), and need to apologize for that. I had overlooked something in my testing...

Here is what you need if you don't want to make the RefBool instances as I suggested (requires more legwork, not recommended):

/// Mutates a boolean:
func toggle(_ boolean: inout Bool) -> Bool {
  boolean ? (boolean = false) : (boolean = true)
  return boolean
}

/// Static state manager for Booleans
struct IsOn {

    private static var
    _previewAudio  = false,
    _previewVisual = false,
    _timerDisplal  = false,
    _quickStart    = false

    enum State { case toggle, get }

   static func previewAudio(_ toggleVal: State = .get) -> Bool {
    if toggleVal == .toggle { toggle(&_previewAudio) }; return _previewAudio
  }

   // ... others
}

---

Testing:

let referenceToPA = IsOn.previewAudio

print ( IsOn.previewAudio() ) // False (default pram works)
print ( referenceToPA(.get) ) // False (can't use default pram)

referenceToPA(.toggle) 

print ( IsOn.previewAudio() ) // True
print ( referenceToPA(.get) ) // True

IsOn.previewAudio(.toggle)

print ( IsOn.previewAudio() ) // False
print ( referenceToPA(.get) ) // False

---

---

---

But honestly, it would be easier to just do the RefBool from my other answer, then you wouldn't need the enum or the functions:

/// Holds a boolean in .val:
final class RefBool { var val: Bool; init(_ boolean: Bool) { val = boolean } }

/// Static state manager for Booleans
struct IsOn {
    static var
      previewAudio  = RefBool(false),
      previewVisual = RefBool(false),
      timerDisplal  = RefBool(false),
      quickStart    = RefBool(false)
}

Convenience Funcs (not necessary):

/// Mutates a boolean:
func toggle(_ boolean: inout Bool) -> Bool {
  boolean ? (boolean = false) : (boolean = true)
  return boolean
}

/// Mutates .val:
func toggle(_ refBool: RefBool) -> Bool {
    refBool.val ? (refBool.val = false) : (refBool.val = true)
    return refBool.val
}

Testing2:

let refToPA = IsOn.previewAudio

refToPA.val = true

print(refToPA.val) // true
print(IsOn.previewAudio.val) // true

toggle(&refToPA.val)

print(refToPA.val) // false
print(IsOn.previewAudio.val) // false

toggle(refToPA) // Using our fancy second toggle

print(refToPA.val) // true
print(IsOn.previewAudio.val) // true

Answer 2

try something like that:

Full example

import UIKit

enum ButtonType {
    case PreviewAudio;
    case PreviewVisua;
    case TimerDisplay;
    case QuickStart;
}

class SwitchProperty {

    var type: ButtonType
    var value: Bool

    init (type: ButtonType) {
        self.type = type
        self.value = false
    }

    var description: String {
        var result = "type = \(type)\n"
        result += "value = \(value)"
        return result
    }

    func switchValue() {
        value.invertValue()
    }
}

class GameManager {

    static var previewAudioIsON = SwitchProperty(type: .PreviewAudio)
    static var previewVisuaIsOn = SwitchProperty(type: .PreviewVisua)
    static var timerDisplayIsOn = SwitchProperty(type: .TimerDisplay)
    static var quickStartIsOn = SwitchProperty(type: .QuickStart)

}

class Button: UIButton {
    var switchValue: SwitchProperty
    init (type: ButtonType, frame: CGRect) {
        switch type {
        case .PreviewAudio:
            switchValue = GameManager.previewAudioIsON
        case .PreviewVisua:
            switchValue = GameManager.previewVisuaIsOn
        case .TimerDisplay:
            switchValue = GameManager.timerDisplayIsOn
        case .QuickStart:
            switchValue = GameManager.quickStartIsOn
        }
        super.init(frame: frame)
        addTarget(self, action: #selector(Button.buttonTouched), for: .touchUpInside)
    }

    func buttonTouched() {
        switchValue.switchValue()
        print(switchValue.description)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

extension Bool {
    mutating func invertValue() {
        self = !self
    }
}

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        addButton(type: .PreviewVisua, frame: CGRect(x: 40, y: 40, width: 200, height: 40));
        addButton(type: .PreviewAudio, frame: CGRect(x: 40, y: 100, width: 200, height: 40));
    }

    func addButton(type: ButtonType, frame: CGRect) {
        let button = Button(type: type, frame: frame);
        button.setTitleColor(UIColor.blue, for: .normal)
        button.setTitle("\(type)", for: .normal)
        view.addSubview(button)
    }
}

Properties accsess from another code

// change value
GameManager.previewAudioIsON.value = false
// check type
if (GameManager.previewAudioIsON.type == .PreviewAudio) {
    print("previewAudioIsON")
}

Result