将展示有关如何使用xpre 8.3.3的swift 3在地图视图上创建圆形叠加层的分步方法
在您的主故事板文件中，将地图工具包视图拖到故事板的场景（视图）上，并为其创建出口，在这里我创建了mapView。另外，您还希望在地图上长按时动态创建叠加层，因此将“长按手势识别器”从对象库拖动到mapView上，然后为其创建动作方法，这里我为该对象创建了addRegion（）。
为CLLocationManager类创建一个全局常量，以便可以在每个函数中对其进行访问。在您的viewDidLoad方法中，添加一些代码以获取用户授权。
import UIKit import MapKitclass ViewController: UIViewController { @IBOutlet var mapView: MKMapView! let locationManager = CLLocationManager()override func viewDidLoad() { super.viewDidLoad() locationManager.delegate = self locationManager.requestAlwaysAuthorization() locationManager.requestWhenInUseAuthorization() locationManager.desiredAccuracy = kCLLocationAccuracyBest locationManager.startUpdatingLocation() }只要在长按手势识别器操作方法addRegion（）中执行长按手势识别器，就添加用于生成圆形区域的代码。
@IBAction func addRegion(_ sender: Any) { print("addregion pressed") guard let longPress = sender as? UILongPressGestureRecognizer else {return} let touchLocation = longPress.location(in: mapView) let coordinates = mapView.convert(touchLocation, toCoordinateFrom: mapView) let region = CLCircularRegion(center: coordinates, radius: 5000, identifier: "geofence") mapView.removeOverlays(mapView.overlays) locationManager.startMonitoring(for: region) let circle = MKCircle(center: coordinates, radius: region.radius) mapView.add(circle) }
除非您在地图上渲染圆圈，否则您仍然不会在地图上实际看到圆圈。为此，您需要实现mapviewdelegate的委托。
func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {}- 为了使代码看起来更简洁，您可以在类结束的最后大括号后创建扩展。一个扩展包含CLLocationManagerDelegate的代码，另一个包含MKMapViewDelegate的代码。
extension ViewController: CLLocationManagerDelegate { func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) { locationManager.stopUpdatingLocation() mapView.showsUserLocation = true }}
您应该在委托方法中调用locationManager.stopUpdatingLocation（），以免电池电量耗尽。
extension ViewController: MKMapViewDelegate { func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer { guard let circelOverLay = overlay as? MKCircle else {return MKOverlayRenderer()} let circleRenderer = MKCircleRenderer(circle: circelOverLay) circleRenderer.strokeColor = .blue circleRenderer.fillColor = .blue circleRenderer.alpha = 0.2 return circleRenderer } }在这里，我们在屏幕上绘制实际的圆。
最终代码应如下所示。
import UIKitimport MapKitclass ViewController: UIViewController { @IBOutlet var mapView: MKMapView! let locationManager = CLLocationManager() override func viewDidLoad() { super.viewDidLoad() locationManager.delegate = self locationManager.requestAlwaysAuthorization() locationManager.requestWhenInUseAuthorization() locationManager.desiredAccuracy = kCLLocationAccuracyBest locationManager.startUpdatingLocation() } // MARK: Long Press Gesture Recognizer Action Method @IBAction func addRegion(_ sender: Any) { print("addregion pressed") guard let longPress = sender as? UILongPressGestureRecognizer else {return} let touchLocation = longPress.location(in: mapView) let coordinates = mapView.convert(touchLocation, toCoordinateFrom: mapView) let region = CLCircularRegion(center: coordinates, radius: 5000, identifier: "geofence") mapView.removeOverlays(mapView.overlays) locationManager.startMonitoring(for: region) let circle = MKCircle(center: coordinates, radius: region.radius) mapView.add(circle) }}extension ViewController: CLLocationManagerDelegate { func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) { locationManager.stopUpdatingLocation() mapView.showsUserLocation = true }}extension ViewController: MKMapViewDelegate { func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer { guard let circelOverLay = overlay as? MKCircle else {return MKOverlayRenderer()} let circleRenderer = MKCircleRenderer(circle: circelOverLay) circleRenderer.strokeColor = .blue circleRenderer.fillColor = .blue circleRenderer.alpha = 0.2 return circleRenderer }}
