uipikcerview多个选择值swift ios

Question

我正在使用按钮中的uipickerview我想面对的唯一问题，我希望用户可以从uipickerview中选择多个值，不仅是一个值，还可以在用户选择多个项目时相应地更改背景颜色。请参阅我的代码和图片，您会得到一个想法试图实现的感谢。

@IBOutlet weak var buttonRole: UIButton!    
    var rolesPicker = UIPickerView()
    var toolBar = UIToolbar()
    var userRoles:\[String\] = \["Importer","Creater","Writer","Barber"\]
    var selectedIndex :Int = 0
    
    @IBAction func didTapPickRoles(_ sender: UIButton) {
        rolesPicker = UIPickerView.init()
        rolesPicker.delegate = self
        rolesPicker.dataSource = self
        rolesPicker.backgroundColor = UIColor.white
        rolesPicker.autoresizingMask = .flexibleWidth
        rolesPicker.contentMode = .center
        rolesPicker.frame = CGRect.init(x: 0.0, y: UIScreen.main.bounds.size.height - 300, width: UIScreen.main.bounds.size.width, height: 300)
           self.view.addSubview(rolesPicker)
        toolBar = UIToolbar.init(frame: CGRect.init(x: 0.0, y: UIScreen.main.bounds.size.height - 300, width: UIScreen.main.bounds.size.width, height: 50))
        toolBar.items = \[UIBarButtonItem.init(title: "Done", style: .done, target: self, action: #selector(onDoneButtonTapped))\]
           self.view.addSubview(toolBar)
        rolesPicker.selectRow(selectedIndex, inComponent: 0, animated: true)
        buttonRole.layer.borderWidth = 1
        buttonRole.layer.borderColor = UIColor.gray.cgColor

    }
    
    @objc func onDoneButtonTapped() {
        toolBar.removeFromSuperview()
        rolesPicker.removeFromSuperview()
    }

}
extension PickerViewController: UIPickerViewDelegate, UIPickerViewDataSource {
    
    func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return 1
    }
    
    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        return userRoles.count
    }
    
    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        userRoles\[row\]
    }
    
    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        selectedIndex = row
        buttonRole.setTitle(userRoles\[row\], for: .normal)
}
}