How to display a circle in GMSMapView

Question

I need to display a circle (as with MKCircle) on a GMSMapView. This is easy when using a MKMapView and MKCircle, but can't use MKCircle with GMSMapView. Any ideas?

Update:
This are the current(18.03.2013) options:
1. A ground marker containing a circle image.
2. A a circle made with several segments (polyline).

Edit:
3. Google added a GMSCircle (23.04.2013)

 GMSGroundOverlayOptions *overlayOptions = [GMSGroundOverlayOptions options];
    overlayOptions.icon = [UIImage imageNamed:@"circle"];
    overlayOptions.position = touchMapCoordinate;
    overlayOptions.bearing = 0;
    overlayOptions.zoomLevel = 14.3;
 [mapView addGroundOverlayWithOptions:overlayOptions];

For a circle image 40x40 pixels it looks ok. (radius is approximately 100 m)

Small segmented path solution:

    GMSPolylineOptions *circle = [GMSPolylineOptions options];
    CGPoint touchPoint = [mapView.projection pointForCoordinate:touchMapCoordinate];
    GMSMutablePath *path = [GMSMutablePath path];

    CGPoint circlePoint;

    for (int i = 0; i < 360; i++)
    { 
        circlePoint.x = touchPoint.x + radius * cos(i*M_PI/180);
        circlePoint.y = touchPoint.y + radius * sin(i*M_PI/180);

        CLLocationCoordinate2D aux = [mapView.projection coordinateForPoint:circlePoint];
        [path addCoordinate:aux];
    }

    circle.path = path;
    circle.width = 1;

    [mapView addPolylineWithOptions:circle];

EDIT : 08.05.2013

GMSCircle solution:

     CLLocationCoordinate2D circleCenter = CLLocationCoordinate2DMake(latitude, longitude);
     GMSCircle *circ = [GMSCircle circleWithPosition:circleCenter
                                     radius:1000];

     circ.fillColor = [UIColor blueColor];
     circ.strokeColor = [UIColor redColor];
     circ.strokeWidth = 5;
     circ.map = mapView;

Answer 1

At the moment the SDK doesn't support circles, but there is a feature request to add circles here:

https://code.google.com/p/gmaps-api-issues/issues/detail?id=4971

In the meantime you could maybe fake a circle by drawing a polyline, with several short segments?

Answer 2

It's a bit late since the question is over a year old, but Google searches led me here, so I thought I'd update this. Posterity 4TW!

There is now a GMSCircle which can do, as far as I know, just about everything an MKCircle can.
Google's documentation on the GMSCircle.

// Build a circle for the GMSMapView
GMSCircle *geoFenceCircle = [[GMSCircle alloc] init];
geoFenceCircle.radius = 130; // Meters
geoFenceCircle.position = SOME_CLLOCATION.coordinate; // Some CLLocationCoordinate2D position
geoFenceCircle.fillColor = [UIColor colorWithWhite:0.7 alpha:0.5];
geoFenceCircle.strokeWidth = 3;
geoFenceCircle.strokeColor = [UIColor orangeColor];
geoFenceCircle.map = mapView; // Add it to the map.

It behaves very similarly to an MKCircle (overlay) in that it resizes with the zoom level of the map, etc. Please disregard the blue circle in the center; that's the user location shown on the map view, and I just used the same coordinate for the center point of the GMSCircle.

Super easy. Check out the images:

One zoom level:

And here, we're zoomed out a bit:

Answer 3

func mapView(_ mapView: GMSMapView, didChange position: GMSCameraPosition) {
    // Make sure cicle is a GMSCircle Object  and it is a class variable
    circle.map = nil

    let point = mapView.center
    circle.position = mapView.projection.coordinate(for: point)
    circle.radius = 130.0
    circle.fillColor = .clear
    circle.strokeColor = .black
    circle.strokeWidth = 3.4
    circle.map = mapView
}