谷歌地图iOS版SDK：如何获取准确的经度和纬度，从相机的visibleRegion坐标？(Goog

编辑：现在这是一个确认的错误与此 SDK

我使用谷歌地图iOS版SDK的1.1.1.2311版本，我期待找到边界纬度和屏幕上的可视地图经度坐标。

我使用下面的代码来告诉我，目前的预测是什么：

NSLog(@"\n%@,%@\n%@,%@\n%@,%@\n%@,%@\n",
    [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]);

从阅读标题，似乎它可能不能在相机移动时更新。 很公平...

/**
 * 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).
 */

但是，似乎每一个委托方法被调用时进行更新，所以我试图绘制坐标，以测试他们...

对于我的手机上的以下内容：

在NSLog的从上面的输出给了我以下内容：

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

当使用绘图这些坐标这个我得到的似乎掀起了预测：

这些坐标是整个应用程序启动一致，导致我相信，我要么一直做错了什么，我误解visibleRegion是什么，或者我发现一个bug。 任何人都关心帮助我弄清楚它是哪一个？

Answer 1:

为了得到边界的经度和纬度，你必须执行以下步骤：

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;

最好的问候罗伯特

Answer 2:

我看到您的问题在这里 。 希望他们修复下次更新这个问题。

但是，现在我们可以采取这样的真正的可视区域：

    CGPoint topLeftPoint = CGPointMake(0, 0);
    CLLocationCoordinate2D topLeftLocation =
    [_mapView.projection coordinateForPoint: topLeftPoint];

    CGPoint bottomRightPoint =
    CGPointMake(_mapView.frame.size.width, _mapView.frame.size.height);
    CLLocationCoordinate2D bottomRightLocation =
    [_mapView.projection coordinateForPoint: bottomRightPoint];

    CGPoint topRightPoint = CGPointMake(_mapView.frame.size.width, 0);
    CLLocationCoordinate2D topRightLocation =
    [_mapView.projection coordinateForPoint: topRightPoint];

    CGPoint bottomLeftPoint =
    CGPointMake(0, _mapView.frame.size.height);
    CLLocationCoordinate2D bottomLeftLocation =
    [_mapView.projection coordinateForPoint: bottomLeftPoint];

    GMSVisibleRegion realVisibleRegion;
    realVisibleRegion.farLeft = topLeftLocation;
    realVisibleRegion.farRight = topRightLocation;
    realVisibleRegion.nearLeft = bottomLeftLocation;
    realVisibleRegion.nearRight = bottomRightLocation;

    [self drawPolylineWithGMSVisibleRegion:realVisibleRegion color:[UIColor redColor] width:10.0f forMap:mapView];

绘制折线方法：

- (void)drawPolylineWithGMSVisibleRegion:(GMSVisibleRegion)visibleRegion
                               color:(UIColor*)color
                               width:(double)width
                              forMap:(GMSMapView*)mapView{
    GMSPolylineOptions *rectangle = [GMSPolylineOptions options];
    rectangle.color = color;
    rectangle.width = width;
    GMSMutablePath *path = [GMSMutablePath path];
    [path addCoordinate:visibleRegion.nearRight];
    [path addCoordinate:visibleRegion.nearLeft];
    [path addCoordinate:visibleRegion.farLeft];
    [path addCoordinate:visibleRegion.farRight];
    [path addCoordinate:visibleRegion.nearRight];
    rectangle.path = path;
    [mapView addPolylineWithOptions:rectangle];
}

它的工作原理，甚至在地图使用非默认轴承和角度。

Answer 3:

解决的办法是下载最新版本的SDK（1.2在写这篇文章的时间）的问题已得到修复。

从1.2版本说明：

已解决的问题： - visibleRegion现在报告在视网膜显示设备尺寸正确的区域

下载这里 。

Answer 4:

貌似纬度和经度坐标要打印出来，手动绘制的可能断位/被截断。 ％F默认只打印出到6位小数。

这里有一个相关的问题可能会有所帮助：

如何打印与iOS上的全精度的双？

Answer 5:

也许你给位置管理器错误的准确性..

试着增加它：

locationMgr.desiredAccuracy = kCLLocationAccuracyBest;

电池被耗尽moreyy

文章来源: Google Maps iOS SDK: How do I get accurate latitude and longitude coordinates from a camera's visibleRegion?