如何在swift中将地图置于用户位置的中心？

Question

我正在编写一个应用程序,我有一个嵌入式mapview来显示用户的位置.到目前为止这是我的代码:

class YourCurrentLocation: UIViewController, CLLocationManagerDelegate {

    @IBOutlet weak var mapView: MKMapView!

    var locationManager = CLLocationManager()
    let regionRadius: CLLocationDistance = 1000

    func checkLocationAuthorizationStatus() {
        if CLLocationManager.authorizationStatus() == .AuthorizedWhenInUse {
            mapView.showsUserLocation = true
            centerMapOnLocation(locationManager.location!, map: mapView, radius: regionRadius)
        } else {
            locationManager.requestAlwaysAuthorization() //requestWhenInUseAuthorization()
        }
    }



    func centerMapOnLocation(location: CLLocation, map: MKMapView, radius: CLLocationDistance) {
        let coordinateRegion = MKCoordinateRegionMakeWithDistance(location.coordinate,
            radius * 2.0, radius * 2.0)
        map.setRegion(coordinateRegion, animated: true)
    }


    override func viewDidLoad() {
        super.viewDidLoad()

       // mapView.delegate = self


        if CLLocationManager.locationServicesEnabled()
        {
            //locationManager = CLLocationManager()
            locationManager.delegate = self
            locationManager.requestAlwaysAuthorization()
            locationManager.desiredAccuracy = kCLLocationAccuracyBest
            locationManager.startUpdatingLocation()
            print("location enabled")
            checkLocationAuthorizationStatus()            
        }
        else
        {
            print("Location service disabled");
        }


        // Do any additional setup after loading the view.
    }

}

我还在我的plist中添加了两个条目:

NSLocationAlwaysUsageDescription
NSLocationWhenInUseUsageDescription

而且在我的xcode中,我已经开始在英国伦敦模拟GPS数据.

当我运行应用程序时 - 我看到地图,但伦敦没有标记.我究竟做错了什么？

顺便说一句,我不得不评论这一行:

//mapView.delegate = self

在viewDidLoad(),否则我有错误:

Cannot assign value of type YourCurrentLocation to type MKMapViewDelegate

而且我不确定这是否是问题的一部分.

我希望在显示到用户地图和该地图上标有其位置的点时实现效果.你能帮帮我吗？

Answer 1

代码的问题在于,当用户给出位置权限时,您试图将地图指向用户的位置,而不是等待为CoreLocation您提供实际的用户位置.您需要使用该CLLocationManagerDelegate方法locationManager(_:didUpdateLocations:)时通知您获得了用户的实际位置,并有可以设置地图指向用户的位置.

class ViewController: UIViewController, CLLocationManagerDelegate {

    @IBOutlet var mapView: MKMapView!
    var locationManager: CLLocationManager?

    override func viewDidLoad() {
        super.viewDidLoad()

        locationManager = CLLocationManager()
        locationManager!.delegate = self

        if CLLocationManager.authorizationStatus() == .AuthorizedWhenInUse {
            locationManager!.startUpdatingLocation()
        } else {
            locationManager!.requestWhenInUseAuthorization()
        }
    }

    func locationManager(manager: CLLocationManager, didChangeAuthorizationStatus status: CLAuthorizationStatus) {


        switch status {
        case .NotDetermined:
            print("NotDetermined")
        case .Restricted:
            print("Restricted")
        case .Denied:
            print("Denied")
        case .AuthorizedAlways:
            print("AuthorizedAlways")
        case .AuthorizedWhenInUse:
            print("AuthorizedWhenInUse")
            locationManager!.startUpdatingLocation()
        }
    }

    func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {

        let location = locations.first!
        let coordinateRegion = MKCoordinateRegionMakeWithDistance(location.coordinate, 500, 500)
        mapView.setRegion(coordinateRegion, animated: true)
        locationManager?.stopUpdatingLocation()
        locationManager = nil
    }

    func locationManager(manager: CLLocationManager, didFailWithError error: NSError) {
        print("Failed to initialize GPS: ", error.description)
    }
}