GMSMapView地面覆盖覆盖整个MapView边界

Question

我已经设置了一个UIView来使用谷歌地图显示地图的特定区域。我现在想在这个选定的区域上添加一个图像覆盖，但我不知道如何计算正确的坐标。我已经用中心坐标设置了地图，但叠加需要西北和东南坐标。有人能帮忙吗？我正在试着在一些道路上画一个赛道的图像。

以下是我到目前为止的代码：

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    GMSCameraPosition *camera = [GMSCameraPosition cameraWithLatitude:14.5809268
                                                       longitude:120.975319
                                                            zoom:16.5
                                                         bearing:90
                                                    viewingAngle:0];
    // Indicating the map frame bounds
    mapView_ = [GMSMapView mapWithFrame:self.mapViewOnScreen.bounds camera: camera];
    mapView_.myLocationEnabled = YES;
    // Add as subview the mapview
    [self.mapViewOnScreen addSubview: mapView_];

    //this is where I need to figure out the coordinates but get stuck...
    CLLocationCoordinate2D southWest = CLLocationCoordinate2DMake(40.712216,-74.22655);
    CLLocationCoordinate2D northEast = CLLocationCoordinate2DMake(40.773941,-74.12544);
    GMSCoordinateBounds *overlayBounds = [[GMSCoordinateBounds alloc] initWithCoordinate:southWest
                                                                          coordinate:northEast];

    //Add track image over the road map to show a race track - roads need to match up
    UIImage *icon = [UIImage imageNamed:@"Track.jpg"];
    GMSGroundOverlay *overlay =
    [GMSGroundOverlay groundOverlayWithBounds:overlayBounds icon:icon];
    overlay.bearing = 0;
    overlay.map = mapView_;
    // Creates a marker in the center of the map.
    GMSMarker *marker = [[GMSMarker alloc] init];
    marker.position = CLLocationCoordinate2DMake(14.5809268, 120.975319);
    marker.title = @"Race Day";
    marker.snippet = @"Manila";
    marker.map = mapView_;
}

Answer 1

我还没有尝试过，但在对API做了一些研究之后，我认为你可以通过以下操作来实现你想要的：

GMSProjection *projection = mapView_.projection;
GMSVisibleRegion visibleRegion = [projection visibleRegion];
GMSCoordinateBounds *coordinateBounds = [[GMSCoordinateBounds alloc] initWithRegion:visibleRegion];
CLLocationCoordinate2D northEast = coordinateBounds.northEast;
CLLocationCoordinate2D southWest = coordinateBounds.southWest;

希望这能有所帮助。