地理位置赋能开发，iOS 离不开的地图功能大盘点

一、定位

定位是地图功能的基础。iOS中可以通过CoreLocation框架和CLLocationManager类来实现定位。CLLocationManager是一个单例类，它提供了各种方法来获取设备的位置信息，包括一次性定位和持续定位。

import CoreLocation

class ViewController: UIViewController {
    let locationManager = CLLocationManager()

    override func viewDidLoad() {
        super.viewDidLoad()

        locationManager.delegate = self
        locationManager.requestWhenInUseAuthorization()
        locationManager.startUpdatingLocation()
    }

    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        if let location = locations.first {
            // 使用位置信息
        }
    }
}

二、标注大头针

大头针是地图上用来标记位置的图标。iOS中可以通过MKAnnotation类来创建大头针。MKAnnotation有许多属性，包括坐标、标题和副标题等。

import MapKit

class ViewController: UIViewController {
    let mapView = MKMapView()

    override func viewDidLoad() {
        super.viewDidLoad()

        mapView.delegate = self
        mapView.addAnnotation(MKPointAnnotation())
    }

    func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
        if let annotation = annotation as? MKPointAnnotation {
            let view = MKPinAnnotationView(annotation: annotation, reuseIdentifier: "pin")
            view.canShowCallout = true
            return view
        }

        return nil
    }
}

三、划线

划线是地图上用来连接两个或多个点的一条线。iOS中可以通过MKPolyline类来创建划线。MKPolyline有许多属性，包括点的数组、颜色和宽度等。

import MapKit

class ViewController: UIViewController {
    let mapView = MKMapView()

    override func viewDidLoad() {
        super.viewDidLoad()

        mapView.delegate = self
        mapView.addOverlay(MKPolyline())
    }

    func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
        if let overlay = overlay as? MKPolyline {
            let renderer = MKPolylineRenderer(polyline: overlay)
            renderer.strokeColor = UIColor.blue
            renderer.lineWidth = 3
            return renderer
        }

        return MKOverlayRenderer()
    }
}

四、路径规划

路径规划是地图上用来计算两点之间的最佳路径的功能。iOS中可以通过MKDirectionsRequest类和MKDirections类来实现路径规划。

import MapKit

class ViewController: UIViewController {
    let mapView = MKMapView()

    override func viewDidLoad() {
        super.viewDidLoad()

        mapView.delegate = self
        let request = MKDirectionsRequest()
        request.source = MKMapItem(placemark: MKPlacemark(coordinate: CLLocationCoordinate2D(latitude: 37.33233141, longitude: -122.0312186)))
        request.destination = MKMapItem(placemark: MKPlacemark(coordinate: CLLocationCoordinate2D(latitude: 37.30922958, longitude: -122.0298243)))
        request.transportType = .automobile

        let directions = MKDirections(request: request)
        directions.calculate { (response, error) in
            if let response = response {
                mapView.addOverlay(response.routes[0].polyline)
            }
        }
    }

    func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
        if let overlay = overlay as? MKPolyline {
            let renderer = MKPolylineRenderer(polyline: overlay)
            renderer.strokeColor = UIColor.blue
            renderer.lineWidth = 3
            return renderer
        }

        return MKOverlayRenderer()
    }
}

五、导航

导航是地图上用来指导用户从一个地方到另一个地方的功能。iOS中可以通过MKNavigationController类来实现导航。

import MapKit

class ViewController: UIViewController {
    let mapView = MKMapView()

    override func viewDidLoad() {
        super.viewDidLoad()

        mapView.delegate = self
        let request = MKDirectionsRequest()
        request.source = MKMapItem(placemark: MKPlacemark(coordinate: CLLocationCoordinate2D(latitude: 37.33233141, longitude: -122.0312186)))
        request.destination = MKMapItem(placemark: MKPlacemark(coordinate: CLLocationCoordinate2D(latitude: 37.30922958, longitude: -122.0298243)))
        request.transportType = .automobile

        let directions = MKDirections(request: request)
        directions.calculate { (response, error) in
            if let response = response {
                let navigationController = MKNavigationController(rootViewController: MKMapViewController(map: mapView))
                navigationController.delegate = self
                navigationController.viewControllers.first?.showsSteps = true
                navigationController.mapViewController.showsTraffic = true
                navigationController.mapViewController.showsScale = true
                navigationController.mapViewController.routeLine = MKPolyline(coordinates: response.routes[0].polyline.coordinates, count: response.routes[0].polyline.pointCount)
                present(navigationController, animated: true)
            }
        }
    }

    func navigationController(_ navigationController: MKNavigationController, didUpdate userLocation: MKUserLocation) {
        mapView.userTrackingMode = .follow
    }
}

六、地理围栏

地理围栏是地图上用来定义一个区域，当用户进入或离开该区域时触发某个事件的功能。iOS中可以通过CLCircularRegion类和CLLocationManager类来实现地理围栏。

import CoreLocation

class ViewController: UIViewController {
    let locationManager = CLLocationManager()

    override func viewDidLoad() {
        super.viewDidLoad()

        locationManager.delegate = self
        locationManager.requestWhenInUseAuthorization()

        let region = CLCircularRegion(center: CLLocationCoordinate2D(latitude: 37.33233141, longitude: -122.0312186), radius: 100, identifier: "MyRegion")
        locationManager.startMonitoring(for: region)
    }

    func locationManager(_ manager: CLLocationManager, didEnterRegion region: CLRegion) {
        // 用户进入地理围栏
    }

    func locationManager(_ manager: CLLocationManager, didExitRegion region: CLRegion) {
        // 用户离开地理围栏
    }
}