如何使两个MKCoordinateRegion之间的联合

问题描述

我试图做两个MKCoordinateRegion之间的联合。

解决方案

有一个 MKMapRectUnion 函数接受两个 MKMapRects ，所以你可以先将每个 MKCoordinateRegion 转换为 MKMapRect 使用 MKCoordinateRegionForMapRect 调用该函数（并将结果转换回 MKCoordinateRegion 函数）。

转换方法可能如下所示：

  - （MKMapRect）mapRectForCoordinateRegion：（MKCoordinateRegion）coordinateRegion 
 {
 CLLocationCoordinate2D topLeftCoordinate = 
 CLLocationCoordinate2DMake（coordinateRegion.center.latitude 
 +（coordinateRegion.span.latitudeDelta / 2.0），
 coordinateRegion.center.longitude 
  - （coordinateRegion.span.longitudeDelta / 2.0））; 
 
 MKMapPoint topLeftMapPoint = MKMapPointForCoordinate（topLeftCoordinate）; 
 
 CLLocationCoordinate2D bottomRightCoordinate = 
 CLLocationCoordinate2DMake（coordinateRegion.center.latitude 
  - （coordinateRegion.span.latitudeDelta / 2.0），
 coordinateRegion.center.longitude 
 +（coordinateRegion.span.longitudeDelta / 2.0））; 
 
 MKMapPoint bottomRightMapPoint = MKMapPointForCoordinate（bottomRightCoordinate）; 
 
 MKMapRect mapRect = MKMapRectMake（topLeftMapPoint.x，
 topLeftMapPoint.y，
 fabs（bottomRightMapPoint.x-topLeftMapPoint.x），
 fabs（bottomRightMapPoint.y- topLeftMapPoint.y））; 
 
 return mapRect; 
} 
  

然后，实际做联合：

MKCoordinateRegion region1 = ...
MKCoordinateRegion region2 = ...

MKMapRect mapRect1 = [self mapRectForCoordinateRegion：region1];
MKMapRect mapRect2 = [self mapRectForCoordinateRegion：region2];

MKMapRect mapRectUnion = MKMapRectUnion（mapRect1，mapRect2）;

MKCoordinateRegion regionUnion = MKCoordinateRegionForMapRect（mapRectUnion）;


I'm trying to do the union between two MKCoordinateRegion. Does anybody have an idea on how to do this?

解决方案

There is a MKMapRectUnion function which accepts two MKMapRects so you could first convert each MKCoordinateRegion to an MKMapRect and then call that function (and convert the result back to an MKCoordinateRegion using the MKCoordinateRegionForMapRect function).

The conversion method might look like this:

- (MKMapRect)mapRectForCoordinateRegion:(MKCoordinateRegion)coordinateRegion
{
    CLLocationCoordinate2D topLeftCoordinate = 
        CLLocationCoordinate2DMake(coordinateRegion.center.latitude 
                + (coordinateRegion.span.latitudeDelta/2.0), 
            coordinateRegion.center.longitude 
                - (coordinateRegion.span.longitudeDelta/2.0));

    MKMapPoint topLeftMapPoint = MKMapPointForCoordinate(topLeftCoordinate);

    CLLocationCoordinate2D bottomRightCoordinate = 
        CLLocationCoordinate2DMake(coordinateRegion.center.latitude 
                - (coordinateRegion.span.latitudeDelta/2.0), 
            coordinateRegion.center.longitude 
                + (coordinateRegion.span.longitudeDelta/2.0));

    MKMapPoint bottomRightMapPoint = MKMapPointForCoordinate(bottomRightCoordinate);

    MKMapRect mapRect = MKMapRectMake(topLeftMapPoint.x, 
                            topLeftMapPoint.y, 
                            fabs(bottomRightMapPoint.x-topLeftMapPoint.x), 
                            fabs(bottomRightMapPoint.y-topLeftMapPoint.y));

    return mapRect;
}

Then, to actually do the union:

MKCoordinateRegion region1 = ...
MKCoordinateRegion region2 = ...

MKMapRect mapRect1 = [self mapRectForCoordinateRegion:region1];
MKMapRect mapRect2 = [self mapRectForCoordinateRegion:region2];

MKMapRect mapRectUnion = MKMapRectUnion(mapRect1, mapRect2);

MKCoordinateRegion regionUnion = MKCoordinateRegionForMapRect(mapRectUnion);

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