objective c - Google Maps iOS SDK: How do I get accurate latitude and longitude coordinates from a camera's visibleRegion?

Question

EDIT: This is now a confirmed bug with this SDK

I'm using version 1.1.1.2311 of the Google Maps for iOS SDK, and I'm looking to find the bounding latitude and longitude coordinates for the visible map on screen.

I'm using the following code to tell me what the current projection is:

NSLog(@"
%@,%@
%@,%@
%@,%@
%@,%@
",
    [NSNumber numberWithDouble:mapView.projection.visibleRegion.farLeft.latitude],
    [NSNumber numberWithDouble:mapView.projection.visibleRegion.farLeft.longitude],
    [NSNumber numberWithDouble:mapView.projection.visibleRegion.farRight.latitude],
    [NSNumber numberWithDouble:mapView.projection.visibleRegion.farRight.longitude],
    [NSNumber numberWithDouble:mapView.projection.visibleRegion.nearLeft.latitude],
    [NSNumber numberWithDouble:mapView.projection.visibleRegion.nearLeft.longitude],
    [NSNumber numberWithDouble:mapView.projection.visibleRegion.nearRight.latitude],
    [NSNumber numberWithDouble:mapView.projection.visibleRegion.nearRight.longitude]);

From reading the headers, it seems that it may not be updated when the camera moves. Fair enough...

/**
 * The GMSProjection currently used by this GMSMapView. This is a snapshot of
 * the current projection, and will not automatically update when the camera
 * moves. The projection may be nil while the render is not running (if the map
 * is not yet part of your UI, or is part of a hidden UIViewController, or you
 * have called stopRendering).
 */

But, it appears to update each time the delegate method is called, so I attempted to plot the coordinates to test them...

For the following on my phone:

The output of the NSLog from above gives me the following:

37.34209003645947,-122.0382353290915
37.34209003645947,-122.010769508779
37.30332095984257,-122.0382353290915
37.30332095984257,-122.010769508779

When plotting those coordinates using this I get a projection that seems off:

These coordinates are consistent across app launches which leads me to believe that I'm either consistently doing something wrong, I'm misunderstanding what visibleRegion is, or I've discovered a bug. Anyone care to help me figure out which one it is?

Answer 1

To get the bounding latitude and longitude you have to do the following steps:

GMSCoordinateBounds *bounds = [[GMSCoordinateBounds alloc] initWithRegion:self.googleMapsView.projection.visibleRegion];

CLLocationCoordinate2D northEast = bounds.northEast;
CLLocationCoordinate2D northWest = CLLocationCoordinate2DMake(bounds.northEast.latitude, bounds.southWest.longitude);
CLLocationCoordinate2D southEast = CLLocationCoordinate2DMake(bounds.southWest.latitude, bounds.northEast.longitude);
CLLocationCoordinate2D southWest = bounds.southWest;

Best regards Robert