MKMapView -显示可定制的网格线

import MapKit

class GridOverlay: NSObject, MKOverlay {
    var coordinate: CLLocationCoordinate2D
    var boundingMapRect: MKMapRect
    
    init(mapRect: MKMapRect) {
        boundingMapRect = mapRect
        coordinate = MKCoordinateForMapPoint(MKMapPoint(x: mapRect.midX, y: mapRect.midY))
    }
}

class ViewController: UIViewController, MKMapViewDelegate {
    @IBOutlet weak var mapView: MKMapView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 设置地图中心和缩放级别
        let initialLocation = CLLocation(latitude: 37.7749, longitude: -122.4194)
        let regionRadius: CLLocationDistance = 1000
        let coordinateRegion = MKCoordinateRegion(center: initialLocation.coordinate, latitudinalMeters: regionRadius, longitudinalMeters: regionRadius)
        mapView.setRegion(coordinateRegion, animated: true)
        
        // 创建网格线的矩形范围
        let topLeft = CLLocationCoordinate2D(latitude: 37.8, longitude: -122.5)
        let bottomRight = CLLocationCoordinate2D(latitude: 37.7, longitude: -122.4)
        let topLeftMapPoint = MKMapPoint(topLeft)
        let bottomRightMapPoint = MKMapPoint(bottomRight)
        let mapRect = MKMapRect(x: topLeftMapPoint.x, y: topLeftMapPoint.y, width: bottomRightMapPoint.x - topLeftMapPoint.x, height: bottomRightMapPoint.y - topLeftMapPoint.y)
        
        // 创建网格线覆盖物并添加到地图上
        let gridOverlay = GridOverlay(mapRect: mapRect)
        mapView.addOverlay(gridOverlay)
    }
    
    func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
        if let gridOverlay = overlay as? GridOverlay {
            let renderer = MKOverlayPathRenderer(overlay: gridOverlay)
            renderer.strokeColor = UIColor.red
            renderer.lineWidth = 1.0
            return renderer
        }
        return MKOverlayRenderer()
    }
}