如何使用swift 4在GMSMapView上添加按钮

import GoogleMaps

class ViewController: UIViewController {

    var mapView: GMSMapView!

    override func viewDidLoad() {
        super.viewDidLoad()

        let camera = GMSCameraPosition.camera(withLatitude: 37.7749, longitude: -122.4194, zoom: 12.0)
        mapView = GMSMapView.map(withFrame: CGRect.zero, camera: camera)
        mapView.delegate = self // 如果需要处理地图事件，可以设置代理
        view = mapView
    }
}

let button = UIButton(type: .custom)
button.frame = CGRect(x: 16, y: 16, width: 100, height: 40)
button.setTitle("按钮", for: .normal)
button.setTitleColor(.white, for: .normal)
button.backgroundColor = .blue
button.addTarget(self, action: #selector(buttonTapped), for: .touchUpInside)
mapView.addSubview(button)

@objc func buttonTapped() {
    // 在这里处理按钮点击事件
    print("按钮被点击了！")
}