如何在google maps swift中取消选择标记

var selectedMarker: GMSMarker?

func mapView(_ mapView: GMSMapView, didTap marker: GMSMarker) -> Bool {
    // 取消之前选中的标记
    selectedMarker?.icon = UIImage(named: "unselected_marker_icon")
    
    // 设置当前选中的标记
    selectedMarker = marker
    selectedMarker?.icon = UIImage(named: "selected_marker_icon")
    
    return true
}

func mapView(_ mapView: GMSMapView, didTapAt coordinate: CLLocationCoordinate2D) {
    // 取消选中的标记
    selectedMarker?.icon = UIImage(named: "unselected_marker_icon")
    selectedMarker = nil
}