Calculate Google Map length in meters with zoom level in #Objective-C (converted from #JavaScript) #iOS #Swift

mapViewController.m

- (void)mapView:(GMSMapView*)mapView idleAtCameraPosition:(GMSCameraPosition*)position
{
    CLLocationCoordinate2D topLeft = mapView.projection.visibleRegion.farLeft;
    CLLocationCoordinate2D bottomLeft = mapView.projection.visibleRegion.nearLeft;
    double lat = fabs(topLeft.latitude - bottomLeft.latitude);
    double mpp = cos(lat * M_PI / 180) * 2 * M_PI * 6378137 / (256 * pow(2, mapView.camera.zoom));
    double distance = mpp * mapView.frame.size.width;
    [[SearchManager shareInstance] distance: distance];
}

original.js

var metersPerPixel = Math.cos(lat * Math.PI/180) * 2 * Math.PI * 6378137 / (256 * Math.pow(2, zoom));

Swift answer for 2019

/// Radius of the visible region shown on the map (in meters)
private var visibleRadius: Double {
    // Get CLLocation for top-left of map
    let topLeft = CGPoint.zero
    let topLeftCoordinate = mapView.projection.coordinate(for: topLeft)
    let topLeftLocation = CLLocation(latitude: topLeftCoordinate.latitude,
                                       longitude: topLeftCoordinate.longitude)
    
    // Get CLLocation for bottom-right of map
    let bottomRight = CGPoint(x: mapView.bounds.width, y: mapView.bounds.height)
    let bottomRightCoordinate = mapView.projection.coordinate(for: bottomRight)
    let bottomRightLocation = CLLocation(latitude: bottomRightCoordinate.latitude,
                                         longitude: bottomRightCoordinate.longitude)
    
    // Radius is half of distance from top-left to bottom-right
    return Double(bottomRightLocation.distance(from: topLeftLocation) / 2)
}

@chrischute thank you, works perfect

👍