(Using iOS 5 and Xcode 4.2)
I have an MKMapView and want to draw a circle of 1000m radius around the user location.
On the surface it would seem that implementing the mapView:viewForAnnotation: map view delegate method, and adding a custom MKAnnotationView for the users location, would be a perfect solution. It would look something like this:
- (MKAnnotationView *)mapView:(MKMapView *)mapView
viewForAnnotation:(id <MKAnnotation>)annotation
{
// If it's the user location, return my custom MKAnnotationView.
if ([annotation isKindOfClass:[MKUserLocation class]]) {
return myCustomAnnotationView;
} else {
return nil;
}
}
However annotations on the map don't scale when you zoom in and out of the map.
So I tried adding an overlay (because overlays scale with the map), using the MKCircle class and setting its co-ordinates to the latest co-ordinates from my locationManger/map view delegate. However as the coordinate property of MKCircle is readonly, I'm having to remove the overlay then add a new one each time the user moves. Causing a noticeable flicker as it happens.
Is there any way to make an annotation scale seamlessly as the map view is scaled in and out? Or is there a good way to make an overlay move seamlessly with changes in the users location?
I would be very grateful for your help :)
Try a custom overlay. Add this in viewDidLoad:
MKCircle *circle = [MKCircle circleWithCenterCoordinate:userLocation.coordinate radius:1000];
[map addOverlay:circle];
userLocation can be obtained by storing the MKUserLocationAnnotation as a property. Then, to actually draw the circle, put this in the map view's delegate:
- (MKOverlayRenderer *)mapView:(MKMapView *)map viewForOverlay:(id <MKOverlay>)overlay
{
MKCircleRenderer *circleView = [[MKCircleRenderer alloc] initWithOverlay:overlay];
circleView.strokeColor = [UIColor redColor];
circleView.fillColor = [[UIColor redColor] colorWithAlphaComponent:0.4];
return circleView;
}