地理围栏区域半径大于MKCircle半径

Question

我正在构建一个应用程序来检测您是否在地图上绘制的区域中。看来，当我测试它时，实际地理围栏区域的半径大于我绘制的圆。我的代码如下：

 func setupGeoFence() {
    let radius = 150
    let location = CLLocation(latitude: 44, longitude: -79)
    geofenceRegion = CLCircularRegion(center: location.coordinate, radius: CLLocationDistance(radius), identifier: "location")
    removeRadiusCircle(mapView: mapView)
    addRadiusCircle(location: location, radius: CLLocationDistance(Float(radius)), mapView: mapView)
    geofenceRegion?.notifyOnExit = true
    geofenceRegion?.notifyOnEntry = true
    self.locationManager.startMonitoring(for: geofenceRegion!)
    self.locationManager.requestState(for: geofenceRegion!)
}
func addRadiusCircle(location: CLLocation,radius: CLLocationDistance, mapView: MKMapView){
    let circle = MKCircle(center: location.coordinate, radius: radius)
    let pin = MKPointAnnotation()
    pin.coordinate = location.coordinate
    mapView.addAnnotation(pin)
    mapView.add(circle)
}