如何使两个MKCoordinateRegion联合

Question

我正在尝试对两个MKCoordinateRegion进行合并。有人知道如何做吗？

- foux

Answer 1

有一个MKMapRectUnion函数，它接受两个MKMapRects，因此您可以首先将每个MKCoordinateRegion转换为MKMapRect，然后调用该函数（并使用MKCoordinateRegionForMapRect函数将结果转换回MKCoordinateRegion）。

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，实际执行并集操作：

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

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

MKMapRect mapRectUnion = MKMapRectUnion(mapRect1, mapRect2);

MKCoordinateRegion regionUnion = MKCoordinateRegionForMapRect(mapRectUnion);

- user467105

Answer 2

如果有人正在寻找使用扩展的Swift等效代码，

extension MKCoordinateRegion {
    func mapRectForCoordinateRegion() -> MKMapRect {
        let dLat = span.latitudeDelta / 2.0
        let dLon = span.longitudeDelta / 2.0

        let topLeft = MKMapPointForCoordinate(
            CLLocationCoordinate2DMake(center.latitude + dLat, center.longitude - dLon))
        let botRight = MKMapPointForCoordinate(
            CLLocationCoordinate2DMake(center.latitude - dLat, center.longitude + dLon))

        return MKMapRectMake(
            topLeft.x,
            topLeft.y,
            fabs(botRight.x - topLeft.x),
            fabs(botRight.y - topLeft.y))
    }

    func unionWith(region: MKCoordinateRegion) -> MKCoordinateRegion {
        let union = MKMapRectUnion(
            self.mapRectForCoordinateRegion(),
            region.mapRectForCoordinateRegion())

        return MKCoordinateRegionForMapRect(union)
    }
}

并且可以像这样使用

let region1 = ...
let region2 = ...

let regionUnion = region1.unionWith(region2)

- Joel Jeske

Answer 3

我在4.3和5.0上做了一些测试，似乎转换不正确

UIImageView *imageView = [[UIImageView alloc] initWithImage:[[UIImage imageNamed:@"heart.png"] imageByScalingProportionallyToSize:CGSizeMake(100, 100)]];
imageView.frame = CGRectMake(0, 0, 100, 100);
imageView.center = [mapView convertCoordinate:mapView.centerCoordinate toPointToView:canvasView];
[canvasView addSubview:imageView];

MKCoordinateRegion region = [mapView convertRect:imageView.frame toRegionFromView:canvasView];
MKMapRect maprect;
for (int i = 0; i < 5; i ++)
{
    maprect = [mapView mapRectForCoordinateRegion:region];
    NSLog(@"%f, %f, %f, %f", region.center.latitude, region.center.longitude, region.span.latitudeDelta, region.span.longitudeDelta);
    NSLog(@"%f, %f, %f, %f", maprect.origin.x, maprect.origin.y, maprect.size.width, maprect.size.height);
    region = MKCoordinateRegionForMapRect([mapView mapRectForCoordinateRegion:region]);
}

14.718256，-40.078125，63.837150，70.312500
78118912.000000，94811514.406252，52428800.000000，52428799.999997
17.416993，-40.078125，63.837150，70.312500
78118912.000000，91803983.982924，52428800.000000，53344239.567355
20.649080，-40.078125，63.837150，70.312500
78118912.000000，87976363.978412，52428800.000000，54699220.734715
24.548345，-40.078125，63.837150，70.312500
78118912.000000，82962597.189840，52428800.000000，56765991.576236
29.305644，-40.078125，63.837150，70.312500
78118912.000000，76093086.024249，52428800.000000，60073659.997575

- newme