使用CLLocationDistance计算最外层的坐标？

Question

我在我的地图上放置了1-12个地标。我在计算最外面的两个点时遇到了麻烦，这样我就可以缩小地图以显示所有的引脚。

CLLocationDistance distLong = [zoomLocationMax.longitude getDistanceFrom:zoomLocationMin.longitude];
CLLocationDistance distLat = [zoomLocationMax.latitude getDistanceFrom:zoomLocationMin.latitude];

MKCoordinateRegion viewRegion = MKCoordinateRegionMakeWithDistance(m_MapView.userLocation.coordinate, distLat, distLong);
MKCoordinateRegion adjustedRegion = [m_MapView regionThatFits:viewRegion];

m_MapView.autoresizingMask = (UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight);
[m_MapView setRegion:adjustedRegion animated:YES];

我一直在愚弄上面的代码，但我可以预见到一些问题：

2)我并不真的想让用户的位置作为中心点，理想情况下，我希望以最远的两个点为中心。

任何代码片段、示例或解释都会有很大帮助！

谢谢

编辑以显示zoomLocatin的计算方式。我基本上取对数和后数，并确定最小值和最大值。也不确定这是不是正确的：

CLLocationCoordinate2D zoomLocationMin;
CLLocationCoordinate2D zoomLocationMax;
if (coordinate.latitude < zoomLocationMin.latitude)
    zoomLocationMin.latitude = coordinate.latitude;
if (coordinate.longitude < zoomLocationMin.longitude)
    zoomLocationMin.longitude = coordinate.longitude;
if (coordinate.latitude > zoomLocationMax.latitude)
    zoomLocationMax.latitude = coordinate.latitude;
if (coordinate.longitude > zoomLocationMax.longitude)
    zoomLocationMax.longitude = coordinate.longitude;

Answer 1

也许你应该尝试这个代码来处理与你的地标完全匹配的代码：

- (void)zoomMapViewToFitAnnotations:(MKMapView *)mapView animated:(BOOL)animated
{ 
    NSArray *annotations = mapView.annotations;
    int count = [mapView.annotations count];
    if ( count == 0) { return; } //return if no annotations

    //convert NSArray of id <MKAnnotation> into an MKCoordinateRegion that can be used to set the map size
    //can't use NSArray with MKMapPoint because MKMapPoint is not an id
    MKMapPoint points[count]; //C array of MKMapPoint struct
    for( int i=0; i<count; i++ ) //load points C array by converting coordinates to points
    {
        CLLocationCoordinate2D coordinate = [(id <MKAnnotation>)[annotations objectAtIndex:i] coordinate];
        points[i] = MKMapPointForCoordinate(coordinate);
    }
    //create MKMapRect from array of MKMapPoint
    MKMapRect mapRect = [[MKPolygon polygonWithPoints:points count:count] boundingMapRect];
    //convert MKCoordinateRegion from MKMapRect
    MKCoordinateRegion region = MKCoordinateRegionForMapRect(mapRect);

    //add padding so pins aren't scrunched on the edges
    region.span.latitudeDelta  *= ANNOTATION_REGION_PAD_FACTOR;
    region.span.longitudeDelta *= ANNOTATION_REGION_PAD_FACTOR;
    //but padding can't be bigger than the world
    if( region.span.latitudeDelta > MAX_DEGREES_ARC ) { region.span.latitudeDelta  = MAX_DEGREES_ARC; }
    if( region.span.longitudeDelta > MAX_DEGREES_ARC ){ region.span.longitudeDelta = MAX_DEGREES_ARC; }

    //and don't zoom in stupid-close on small samples
    if( region.span.latitudeDelta  < MINIMUM_ZOOM_ARC ) { region.span.latitudeDelta  = MINIMUM_ZOOM_ARC; }
    if( region.span.longitudeDelta < MINIMUM_ZOOM_ARC ) { region.span.longitudeDelta = MINIMUM_ZOOM_ARC; }
    //and if there is a sample of 1 we want the max zoom-in instead of max zoom-out
    if( count == 1 )
    { 
        region.span.latitudeDelta = MINIMUM_ZOOM_ARC;
        region.span.longitudeDelta = MINIMUM_ZOOM_ARC;
    }
    [mapView setRegion:region animated:animated];
}

因此，您必须定义填充、最大度数圆弧和最小变焦圆弧。对于Ex.应该是这样的：

#define MINIMUM_ZOOM_ARC 0.05 //approximately 1 miles (1 degree of arc ~= 69 miles)
#define ANNOTATION_REGION_PAD_FACTOR 1.25
#define MAX_DEGREES_ARC 360

希望你会喜欢，干杯