serhiybutz

struct MyThemeSettings {
    let appBgColor: UIColor
    let highlightedBgColor: UIColor
    let textColor: UIColor
}

serhiybutz

let lightThemeModel = MyThemeModel(
    appBgColor: .white,
    textColor: .black)

let darkThemeModel = MyThemeModel(
    appBgColor: .darkGray,
    textColor: .white)

serhiybutz

enum MyTheme {
    case light
    case dark
    var settings: MyThemeSettings {
        switch self {
            case .light: return MyThemeSettings.lightTheme
            case .dark: return MyThemeSettings.darkTheme
        }
    }
}

serhiybutz

@objc protocol Themable {
    func applyTheme(_ theme: MyTheme)
}

serhiybutz

import Foundation

final class ThemeManager {
    private var themables = NSHashTable<Themable>
        .weakObjects()

    var theme: MyTheme {
        didSet {
            guard theme != oldValue else { return; }
            apply()

serhiybutz

@objc enum MyTheme: Int {
    case light
    case dark
    var settings: MyThemeSettings {
        switch self {
        case .light: return MyThemeSettings.lightTheme
        case .dark: return MyThemeSettings.darkTheme
        }
    }
}

serhiybutz

import UIKit

// MARK: - Highlighted Label Class
class HighlightedLabel: UILabel {
    override func didMoveToWindow() {
        // Subscribe to theme notifications
        ThemeManager.shared.register(self)
        super.didMoveToWindow()
    }
}

serhiybutz

import Foundation

fileprivate var associatedKey = "ThemerTargetActionStorage"

final class TargetActionStorage {
    private var targetActions: [TargetAction] = []

    static func setup(for target: Any) -> TargetActionStorage {
        let storage = TargetActionStorage()
        objc_setAssociatedObject(

serhiybutz

protocol TargetAction {
    func applyTheme(_ theme: MyTheme)
}

struct AnyTargetActionWrapper<T: AnyObject>: TargetAction {
    weak var target: T?
    let action: (T) -> (MyTheme) -> ()

    func applyTheme(_ theme: MyTheme) -> () {
        if let t = target {

serhiybutz

import Foundation

final class ThemeManager {
    private var targetActionStorages = NSHashTable<TargetActionStorage>
        .weakObjects()

    var theme: MyTheme {
        didSet {
            guard theme != oldValue else { return; }
            apply()