如何在iOS地图上叠加圆圈

Question

我有一个半径和一个位置.

这就是我试图获得圆的边界矩形的方式.

- (MKMapRect)boundingMapRect{

    CLLocationCoordinate2D tmp;
    MKCoordinateSpan radiusSpan = MKCoordinateRegionMakeWithDistance(self.coordinate, 0, self.radius).span;
    tmp.latitude = self.coordinate.latitude - radiusSpan.longitudeDelta;
    tmp.longitude = self.coordinate.longitude - radiusSpanSpan.longitudeDelta;

    MKMapPoint upperLeft = MKMapPointForCoordinate(tmp);
    MKMapRect bounds = MKMapRectMake(upperLeft.x, upperLeft.y, self.radius * 2, self.radius * 2);

    return bounds;
}

MKMapRectMake(...)似乎想要在地图点测量宽度和高度.如何将半径转换为？

最后我将它呈现如下:

MKMapRect theMapRect = [self.overlay boundingMapRect];
CGRect theRect = [self rectForMapRect:theMapRect];
CGContextAddEllipseInRect(ctx, theRect);
CGContextFillPath(ctx);

半径在地图上似乎最终不等于米,并且似乎也没有正确测量距离.怎么做对了？

我会非常感谢每一个提示.

Answer 1

您应该使用MKCircle.做类似的事情:

CLLocationDistance fenceDistance = 300;
CLLocationCoordinate2D circleMiddlePoint = CLLocationCoordinate2DMake(yourLocation.latitude, yourLocation.longitude);
MKCircle *circle = [MKCircle circleWithCenterCoordinate:circleMiddlePoint radius:fenceDistance];
[yourMapView addOverlay: circle];

并采用下面的MKMapViewDelegate方法,并执行以下操作:

- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id<MKOverlay>)overlay

{
     MKCircleView *circleView = [[[MKCircleView alloc] initWithCircle:(MKCircle *)overlay] autorelease];
     circleView.fillColor = [[UIColor redColor] colorWithAlphaComponent:0.9];
     return circleView;
 }

Answer 2

对于iOS7:

与viewDidLoad中的tdevoy相同:

CLLocationDistance fenceDistance = 300;
CLLocationCoordinate2D circleMiddlePoint = CLLocationCoordinate2DMake(yourLocation.latitude, yourLocation.longitude);
MKCircle *circle = [MKCircle circleWithCenterCoordinate:circleMiddlePoint radius:fenceDistance];
[yourMapView addOverlay: circle];

但委托方法(因为mapView:viewForOverlay:已弃用):

- (MKOverlayRenderer *)mapView:(MKMapView *)mapView rendererForOverlay:(id < MKOverlay >)overlay
{
    MKCircleRenderer *circleR = [[MKCircleRenderer alloc] initWithCircle:(MKCircle *)overlay];
    circleR.fillColor = [UIColor greenColor];

    return circleR;
}