ios - Google Maps iOS SDK：地图上东西点之间的距离

Question

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: 委托方法捕捉​​到移动，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（以米为单位）：

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：

这取决于地图的“东”和“西”是什么意思，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，地图顶部和底部之间的地图宽度以米为单位（靠近赤道的边缘会比边缘更宽以米为单位）离赤道更远）。您放大的越多，差异就会越小。

但是假设你想得到地图左下角和右下角之间的米距离，你可以使用这个：

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 aGMSCoordinateBounds中，然后计算东南角和西南角之间的距离，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它将可见区域的四边形包裹在轴对齐的边界框中。

另一种选择是在地图视图框架的每一侧选择点，然后使用地图视图的投影将它们转换为纬度/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 包含一堆几何助手。

你想要这个功能：

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。两个坐标都必须有效。”

Answer 3

这是查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);
}];