public class SettingsBundleHelper: NSObject {
    ...

    fileprivate struct Keys {
        ...
        static let ToggleAnalytics = "TOGGLE_ANALYTICS"
        ...
    }

    weak var analyticsDelegate: AnalyticToggleDelegate?

    public init(enableSwitching: Bool) {
        self.enableSwitching = enableSwitching

        super.init()
        setupKVO()
    }

    fileprivate func setupKVO() {
        UserDefaults.standard.addObserver(
            self,
            forKeyPath: Keys.ToggleAnalytics,
            options: NSKeyValueObservingOptions.new,
            context: nil
        )
    }

    public var analyticsEnabled: Bool {
        return UserDefaults.standard.bool(forKey: Keys.ToggleAnalytics)
    }

    override public func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey: Any]?, context: UnsafeMutableRawPointer?) {
       if analyticsEnabled {
           analyticsDelegate?.addAnalyticProviders()
       } else {
           analyticsDelegate?.removeAnalyticProviders()
       }
    }

    deinit {
        UserDefaults.standard.removeObserver(self, forKeyPath: Keys.ToggleAnalytics)
    }
    ...
}