MKOverlayRenderer剪切和模糊与变焦iOS

我正在努力解决与MapKit有关的问题。MKOverlayRenderer剪切和模糊与变焦iOS

我创建了一个MKPolygon的列表，根据我的geofence的服务器数据。

+ (MKPolygon *)polygonFromPoints:(NSArray *)points interiorPolygons:(NSArray *)polygons{ 

    NSInteger numberOfCoordinates = [points count]; 
    CLLocationCoordinate2D *polygonPoints = malloc(numberOfCoordinates * sizeof(CLLocationCoordinate2D)); 

    NSInteger index = 0; 
    for (NSArray *pointArray in points) { 
      polygonPoints[index] = CLLocationCoordinate2DMake([pointArray[1] floatValue], [pointArray[0] floatValue]); 
      index++; 
    } 

    MKPolygon *polygon; 
    if (polygons) { 
     polygon = [MKPolygon polygonWithCoordinates:polygonPoints count:numberOfCoordinates interiorPolygons:polygons]; 
    } else { 
     polygon = [MKPolygon polygonWithCoordinates:polygonPoints count:numberOfCoordinates]; 
    } 

    free(polygonPoints); 
    return polygon; }

，并将其添加到地图作为MKOverlayRender

- (MKOverlayRenderer *) mapView:(MKMapView *)mapView rendererForOverlay:(id<MKOverlay>)overlay{ 

    if([overlay isKindOfClass: [MKCircle class]]){ 
     MKCircleRenderer *circleRender = [[MKCircleRenderer alloc] initWithCircle:(MKCircle *)overlay]; 
     circleRender.fillColor = [ [Common colorWithHexString:BlueGeoFence] colorWithAlphaComponent:0.3]; 

     return circleRender; 
    }else if([overlay isKindOfClass: [MKPolygon class]]){ 

     MKPolygonRenderer *polygonRenderer = [[MKPolygonRenderer alloc] initWithPolygon:(MKPolygon *)overlay]; 
     polygonRenderer.fillColor = [ [Common colorWithHexString:BlueGeoFence] colorWithAlphaComponent:0.3]; 

     return polygonRenderer; 
    } 

    return nil; 
}

然而，当我放大或更改地图的位置重叠是削减，并有某种模糊效果。