Using Channels #1

UsingChannels-Delegation-Definition.swift

enum Theme: String {
    case light, dark
}

protocol UserSettingsDelegate {
    func themeDidChange(_ theme: Theme)
}

class UserSettings {
    
    var delegate: UserSettingsDelegate?

    var theme: Theme = .light {
        didSet {
            delegate?.themeDidChange(theme)
        }
    }

    init() { }
}

UsingChannels-Delegation-Usage.swift

class HomeViewController: UIViewController {

    private lazy var userSettings: UserSettings = {
        let settings = UserSettings()
        settings.delegate = self
        return settings
    }()
  
    func didTapOnSettings() {
        let settingsVC = SettingsViewController(userSettings: userSettings)
        present(settingsVC, animated: true)
    }
}

extension HomeViewController: UserSettingsDelegate {
  
    func themeDidChange(_ theme: Theme) {
        // Apply theme here.
    }
}