使用Swift 5在整个谷歌地图上添加图像覆盖

我正在尝试放置一个覆盖整个谷歌地图的图像，从-180º到180º经度。 但每次我尝试这个，图像都不会显示出来。如果我将其中一个坐标（经度）更改为-10º经度，那么只有地图上图像的一半会覆盖整个地图。 我不明白为什么当我使用-180º和180º经度时，图像不能覆盖整个地图

我也使用85.06º和-85.06º作为纬度，但这确实有效

下面是我在代码中使用的内容

}

import UIKit
import GoogleMaps

class MapVC: UIViewController, GMSMapViewDelegate {

@IBOutlet weak var mapView: GMSMapView!

var lat = 33.5
var lon = -11.0

override func viewDidLoad() {
    super.viewDidLoad()
    navigationController?.setNavigationBarHidden(false, animated: true)
    setupImage()
}

func setupImage() {
        let camera = GMSCameraPosition.camera(withLatitude: lat, longitude: lon, zoom: 5)
        let mapView = GMSMapView.map(withFrame: CGRect.zero, camera: camera)
        mapView.isMyLocationEnabled = true
        mapView.delegate = self
        mapView.setMinZoom(3, maxZoom: 8)
        view = mapView
        
        let southWest = CLLocationCoordinate2D(latitude: -85.06, longitude: -180)
        let northEast = CLLocationCoordinate2D(latitude: 85.06, longitude: 180)
        let overlayBounds = GMSCoordinateBounds(coordinate: southWest, coordinate: northEast)

            DispatchQueue.main.async {
                let image = UIImage(systemName: "stop.fill")
                let overlay = GMSGroundOverlay(bounds: overlayBounds, icon: image)
                overlay.bearing = 0
                overlay.map = mapView
    }
}