let pickerController = GroupedColorPickerViewController()
pickerController.didSelect = { [weak self] color, hexString in
    self?.view.backgroundColor = color
    self?.title = hexString
    self?.dismiss(animated: true, completion: nil)
}
pickerController.didClose = { [weak self] in
    self?.dismiss(animated: true, completion: nil)
}
let navController = UINavigationController(rootViewController: pickerController)
present(navController, animated: true, completion: nil)