Google Maps iOS SDK：地图上东西点之间的距离

如何计算地图东点和西点之间的距离（以米为单位）？ 假设用户改变了滚动地图的位置，然后我用mapView：didChangeCameraPosition：delegate方法捕捉到了移动，但我不知道如何计算距离。

Answer 1

这是一个辅助函数，可用于计算两个坐标之间的距离：

double getDistanceMetresBetweenLocationCoordinates( CLLocationCoordinate2D coord1, CLLocationCoordinate2D coord2) { CLLocation* location1 = [[CLLocation alloc] initWithLatitude: coord1.latitude longitude: coord1.longitude]; CLLocation* location2 = [[CLLocation alloc] initWithLatitude: coord2.latitude longitude: coord2.longitude]; return [location1 distanceFromLocation: location2]; } 

更新：

这取决于您在地图的“东”和“西”的含义，因为地图可能会旋转或倾斜。 即使它没有倾斜或旋转，由于地球的曲率，地图的顶部和底部之间的地图宽度将以米为单位（靠近赤道的边缘将比边缘更宽，以米为单位）这是赤道的更远）。 你变化越大，差异越小。

但是假设你想要在地图的左下角和右下角之间获得距离，你可以使用：

 GMSMapView* mapView = ...; CLLocationCoordinate2D bottomLeftCoord = mapView.projection.visibleRegion.nearLeft; CLLocationCoordinate2D bottomRightCoord = mapView.projection.visibleRegion.nearRight; double distanceMetres = getDistanceMetresBetweenLocationCoordinates( bottomLeftCoord, bottomRightCoord); 

如果要考虑旋转/倾斜，可以将可见区域包裹在GMSCoordinateBounds ，然后计算GMSCoordinateBounds和GMSCoordinateBounds之间的距离，例如：

 GMSMapView* mapView = ...; GMSCoordinateBounds* bounds = [[GMSCoordinateBounds alloc] initWithRegion: mapView.projection.visibleRegion]; CLLocationCoordinate2D southWest = bounds.southWest; CLLocationCoordinate2D southEast = CLLocationCoordinate2DMake( bounds.southWest.latitude, bounds.northEast.longitude); double distanceMetres = getDistanceMetresBetweenLocationCoordinates( southWest, southEast); 

但是，这可能比屏幕上实际可见的区域更宽，因为GMSCoordinateBounds将可见区域的四边形包裹在轴对齐的边界框中。

另一个选择是在地图视图的框架的每一侧选择点，然后使用地图视图的投影将这些转换为纬度/经度，例如：

 GMSMapView* mapView = ...; CGPoint middleLeftPoint = CGPointMake( 0, mapView.frame.size.height / 2); CGPoint middleRightPoint = CGPointMake( mapView.frame.size.width, mapView.frame.size.height / 2); CLLocationCoordinate2D middleLeftCoord = [mapView.projection coordinateForPoint: middleLeftPoint]; CLLocationCoordinate2D middleRightCoord = [mapView.projection coordinateForPoint: middleRightPoint]; double distanceMetres = getDistanceMetresBetweenLocationCoordinates( middleLeftCoord, middleRightCoord); 

Answer 2

Google Maps iOS SDK包含许多几何帮助程序 。

你想要这个function：

 GMSGeometryDistance (CLLocationCoordinate2D from, CLLocationCoordinate2D to) -> CLLocationDistance 

“返回地球上两个坐标之间的大圆距离（以米为单位）。这是球体上两个坐标之间的最短距离。两个坐标必须有效。”

Answer 3

下面是寻找两点之间距离的代码

  AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager]; [manager.requestSerializer setCachePolicy:NSURLRequestReloadIgnoringLocalCacheData]; NSString *urlString =@"https://maps.googleapis.com/maps/api/directions/json"; NSDictionary *dictParameters = @{@"origin" : [NSString stringWithFormat:@"%@",_sourceAdd], @"destination" : [NSString stringWithFormat:@"%@",_destinationAdd], @"mode" : @"driving", @"key":@"AIzaSyD9cWTQkAxemELVXTNUCALOmzlDv5b9Dhg"}; [manager GET:urlString parameters:dictParameters success:^(AFHTTPRequestOperation *operation, id responseObject) { NSDictionary *arr=responseObject[@"routes"][0][@"legs"]; NSMutableArray *loc=[[NSMutableArray alloc]init]; NSString *dis,*dur; loc=[[arr valueForKey:@"distance"]valueForKey:@"text"]; dis=loc[0]; loc=[[arr valueForKey:@"duration"]valueForKey:@"text"]; dur=loc[0]; UIAlertView *av=[[UIAlertView alloc]initWithTitle:@"Route Info" message:[NSString stringWithFormat:@"Distance:%@ \nDuration:%@",dis,dur] delegate:nil cancelButtonTitle:@"Okay" otherButtonTitles:nil, nil]; [av show]; } failure:^(AFHTTPRequestOperation *operation, NSError *error) { NSLog(@"Error: %@", error); }];