For starter you can use below code but you will have to tweak it little to make it of your use:
in .h file confirm to MKMapViewDelegate
@interface MapViewController : UIViewController <MKMapViewDelegate>
Then,
in "viewDidLoad"
CLLocationCoordinate2D center = {X cordinate, Y cordinate};
//--> Add overlay
MKCircle *mCircle = [MKCircle circleWithCenterCoordinate:center radius:1000]; //set radius as per your need
[self.mapView addOverlay:mCircle];
Then,
- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id<MKOverlay>)overlay
{
MKCircleView *cirView = [[MKCircleView alloc] initWithOverlay:overlay];
[cirView setFillColor:[UIColor redColor]];
[cirView setStrokeColor:[UIColor blackColor]];
[cirView setAlpha:0.3f];
return cirView;
}
I think this should get you started.