如何在Swift中创建MKCircle？

Question

Iv一直在四处寻找一个很好的解释，说明如何使用SWIFT2.0为MKCircle编写MapView注释，但我似乎找不到足够的解释。有人可以发布一些示例代码来展示如何创建MKCircle注释吗？这是我用来绘制地图和获取坐标的代码。

let address = self.location

let geocoder = CLGeocoder()

    geocoder.geocodeAddressString(address, completionHandler: {(placemarks, error) -> Void in
        if((error) != nil){
            print("Error", error)
        }
        if let placemark = placemarks?.first {
            let coordinates:CLLocationCoordinate2D = placemark.location!.coordinate

            self.locationCoordinates = coordinates
            let span = MKCoordinateSpanMake(0.005, 0.005)
            let region = MKCoordinateRegion(center: self.locationCoordinates, span: span)
            self.CIMap.setRegion(region, animated: true)

            let annotation = MKPointAnnotation()
            annotation.coordinate = self.locationCoordinates
            self.CIMap.addAnnotation(annotation)

            self.CIMap.layer.cornerRadius = 10.0

            self.CIMap.addOverlay(MKCircle(centerCoordinate: self.locationCoordinates, radius: 1000))
        }
    })

Answer 1

将展示如何使用xcode 8.3.3在地图视图上创建循环覆盖的步骤。

在您的主情节提要文件中，将mapView视图拖到情节提要的场景(视图)上，并为同样的场景创建出口，这里我创建了mapView。此外，无论何时在地图上按长键，您都希望动态地创建覆盖，因此将long press手势识别器从对象库拖到mapView上，然后为相同的操作方法创建操作方法，这里我为相同的对象创建了addRegion()。

1. 为CLLocationManager类创建一个全局常量，以便可以在每个函数中访问它。在您的viewDidLoad方法中，添加一些代码以获得用户的授权。 导入UIKit导入MapKit类ViewController: UIViewController { @IBOutlet : MKMapView！设locationManager = CLLocationManager()覆盖func viewDidLoad() { super.viewDidLoad() locationManager.delegate = self locationManager.requestAlwaysAuthorization() locationManager.requestAlwaysAuthorization locationManager.desiredAccuracy = kCLLocationAccuracyBest locationManager.startUpdatingLocation() }
2. 在您的长按压手势识别器动作方法addRegion()中添加代码以生成循环区域。 @IBAction func addRegion(_ longPress : Any) { print("addregion按下“)保护让longPress=发件人作为？UILongPressGestureRecognizer center{ let } let touchLocation = longPress.location(in: mapView) let坐标= mapView.convert(touchLocation，toCoordinateFrom: mapView) let region =CLCircularRegion(中心:坐标，半径: 5000，标识符："geofence") mapView.removeOverlays(mapView.overlays) locationManager.startMonitoring(for: mapView)让圆=MKCircle(中心:坐标，radius: region.radius) mapView.add(圆)}

不过，在地图上呈现圆圈之前，您不会在地图上实际看到圆圈。为此，您需要实现implement委托的委托。

        func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {}

1. 为了使代码看起来更简洁，您可以在类结束的最后一个大括号之后创建扩展。一个扩展包含CLLocationManagerDelegate的代码，另一个包含MKMapViewDelegate的代码。 扩展ViewController: CLLocationManagerDelegate { func locationManager(_ locationManager: CLLocationManager，didUpdateLocations locations: CLLocation) { locationManager.stopUpdatingLocation() mapView.showsUserLocation = true }

您应该在委托方法中调用locationManager.stopUpdatingLocation()，这样电池就不会耗尽。

        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
            }
        }

这里我们在屏幕上画一个实际的圆圈。

最后的代码应该如下所示。

import UIKit
import MapKit

class 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
    }
}

Answer 2

首先，您需要将MKMapViewDelegate添加到类防御中。

 mapView.delegate = self 

在viewDidLoad中将映射委托设置为self。

设置注释

mapView.addOverlay(MKCircle(centerCoordinate: CLLocationCoordinate2D, radius: CLLocationDistance))

现在应该在mapView委托中调用rendererForOverlay，并在那里绘制它。

func mapView(mapView: MKMapView, rendererForOverlay overlay: MKOverlay) -> MKOverlayRenderer {
    if let overlay = overlay as? MKCircle {
        let circleRenderer = MKCircleRenderer(circle: overlay)
        circleRenderer.fillColor = UIColor.blueColor()
        return circleRenderer
    }
}

此外，您还需要导入MapKit以使其全部编译

Answer 3

重叠仅仅是一组数字。在地图视图中可见的东西是一个覆盖渲染器。您必须实现mapView:rendererForOverlay:来提供覆盖渲染器；否则，您将什么也看不到。