[iPhone]在Google地图上的某个位置绘制圆圈

Question

I am new to iPhone programming. I want to write an application using CoreLocation and Mapkit API. I have been able to find and add pins for the current location. Now, I am trying to draw a circle around the location, but I am not sure how to go about doing that. I'd appreciate any pointers, thanks.

Answer 1

I thought i have got same question with you. And i have found this questions answer, it was helped me a lot, i hope this will be help to you. Drawing a Point, Line, Polygon on top of MKMapview

Answer 2

I know this was originally tagged iOS SDK 3.0 , but I assume that was because at the time, that was the current SDK. If somebody is looking for the answer to this, but can use iOS 4.0+, then here's my solution.

So, I assume you have a UIViewController , that owns a MKMapView .

  @interface MapViewController : UIViewController<MKMapViewDelegate> {
  @private
    MKMapView* mapView;
  }
  @property (nonatomic, retain) IBOutlet MKMapView* mapView;
  @end

and you setup your connections in Interface Builder (XCode now) to connect the actual MKMapView to the mapView outlet. And then you have some variable that contains the location you want to draw a circle around: location . You simply need to create a MKCircle , and add it to your mapView as an overlay :

  CLLocationCoordinate2D location = [self getTheLocationSomehow];
  CLLocationDistance radius = 50.0;   // in meters
  MKCircle* circle = [MKCircle circleWithCenterCoordinate: location radius: radius];
  [mapView addOverlay:circle];

If you want to customize the look of your circle, your view controller could implement MKMapViewDelegate and implement mapView:viewForOverlay: like so:

- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id <MKOverlay>)overlay {
    MKCircle* circle = overlay;
    MKCircleView* circleView = [[[MKCircleView alloc] initWithCircle: circle] autorelease];
    // make the circle red with some transparency and stroke
    circleView.fillColor = [UIColor colorWithRed:1.0 green:0.0 blue:0.0 alpha:0.25];
    circleView.strokeColor = [UIColor redColor];
    circleView.lineWidth = 2.0;

    return circleView;
}

Remember to set mapView.delegate = self in the view controller code (eg viewDidLoad ) or graphically via Interface Builder .