如何检测MKMapView被缩小/缩小？

import UIKit
import MapKit

class ViewController: UIViewController, MKMapViewDelegate {

    @IBOutlet weak var mapView: MKMapView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        mapView.delegate = self
    }
    
    func mapView(_ mapView: MKMapView, regionDidChangeAnimated animated: Bool) {
        let zoomLevel = Int(log2(mapView.region.span.longitudeDelta * MKMapSize.world.width / 256) + 1)
        print("当前缩放级别：\(zoomLevel)")
        
        if zoomLevel < 10 {
            print("地图被缩小了")
        } else {
            print("地图被放大了")
        }
    }
}