问题:

I am working with Google maps and I am able to center the map to the GMSMarker by using

 GMSCameraPosition *camera =
    [[GMSCameraPosition alloc] initWithTarget:marker.position
                                         zoom:MAP_ZOOM_LEVEL
                                      bearing:0
                                 viewingAngle:0];
    [mapView animateToCameraPosition:camera];

I am showing a custom callout of size 200*150 and part of it gets hidden when the camera position is changed but I want the callout to be in the center and the map point to be below it. Any ideas how to do this.

回答1:

Have a look at using GMSProjection. To shift the center of the map 100px from the markers location you would do something like:

- (BOOL)mapView:(GMSMapView *)mapView didTapMarker:(GMSMarker *)marker {
  CGPoint point = [mapView_.projection pointForCoordinate:marker.position];
  point.x = point.x + 100;
  GMSCameraUpdate *camera =
      [GMSCameraUpdate setTarget:[mapView_.projection coordinateForPoint:point]];
  [mapView_ animateWithCameraUpdate:camera];
  return YES;
}

回答2:

Swift 4, 3

func mapView(_ mapView: GMSMapView, didTap marker: GMSMarker) -> Bool {
    var point:CGPoint = mapView.projection.point(for: marker.position)
    point.x = point.x + 100

    let camera:GMSCameraUpdate = GMSCameraUpdate.setTarget(mapView.projection.coordinate(for: point))
    mapView.animate(with: camera)

    return true
}