MapKit 中的中心位置在 UiLabel 中不可见

Posted 2023-02-27

【中文标题】MapKit 中的中心位置在 UiLabel 中不可见

【英文标题】：The centre locations in MapKit is not visible in the UiLabel

【发布时间】：2018-11-02 07:53:46

【问题描述】：

无法在标签中显示地图的中心位置！

导入 UIKit 导入 MapKit 导入核心位置

类视图控制器：UIViewController、CLLocationManagerDelegate、MKMapViewDelegate

@IBOutlet weak var myMapView: MKMapView!

@IBOutlet weak var addressLabel: UILabel!

let locationManager = CLLocationManager()
let regionInMeters: Double = 10000
var previousLocation: CLLocation?


override func viewDidLoad() 
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    checkLocationServices()



func setupLocationManager() 
    locationManager.delegate = self
    locationManager.desiredAccuracy = kCLLocationAccuracyBest


func centerViewOnUserLocation() 
    if let location = locationManager.location?.coordinate 
        let region = MKCoordinateRegion.init(center: location, latitudinalMeters: regionInMeters, longitudinalMeters: regionInMeters)
        myMapView.setRegion(region, animated: true)
    



// the Location service
func checkLocationServices() 
    if CLLocationManager.locationServicesEnabled() 
        setupLocationManager()
        checkLocationAuthorisation()

     else 
        //show user to turn ON the services
    


func checkLocationAuthorisation() 
    switch CLLocationManager.authorizationStatus() 
    case .authorizedWhenInUse:
        // do the stuff
        startTrackingLocation()

    case .denied:
        //Alert to turn ON the permissions
        break
    case .notDetermined:
        locationManager.requestWhenInUseAuthorization()
    case .restricted:
        // Alert to show what's up
        break
    case .authorizedAlways:

        break

    


func startTrackingLocation() 
    myMapView.showsUserLocation = true
    centerViewOnUserLocation()
    locationManager.startUpdatingLocation()
    previousLocation = getCenterLocation(for: myMapView)


func getCenterLocation(for mapView: MKMapView) -> CLLocation 
    let latitude = mapView.centerCoordinate.latitude
    let longitude = mapView.centerCoordinate.longitude

    return CLLocation(latitude: latitude, longitude: longitude)



func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) 
    // We'll be back
    checkLocationAuthorisation()


func mapView(_ mapView: MKMapView, regionDidChangeAnimated animated: Bool) 

    let center = getCenterLocation(for: myMapView)
    let geoCoder = CLGeocoder()

    guard let previousLocation = self.previousLocation else  return 

    guard center.distance(from: previousLocation) > 50 else  return 
    self.previousLocation = center

    geoCoder.reverseGeocodeLocation(center)  [weak self] (placemarks, error) in
        guard let self = self else  return 

        if let _ = error 
            //TODO: Show alert informing the user
            return
        
        guard let placemark = placemarks?.first else 
            //TODO: Show alert informing the user
            return
        

        let streetNumber = placemark.subThoroughfare  ?? ""
        let streetName = placemark.subThoroughfare ?? ""

        DispatchQueue.main.async 
            self.addressLabel.text = "\(streetNumber) \(streetName)"
        
    



@IBAction func satelliteView(_ sender: Any) 
    myMapView.mapType = MKMapType.satellite



@IBAction func hybridView(_ sender: Any) 
    myMapView.mapType = MKMapType.hybrid



@IBAction func standardView(_ sender: Any) 
    myMapView.mapType = MKMapType.standard



@IBAction func findDirections(_ sender: Any) 

应用程序中的标签应该显示地图的中心位置（图钉）。但是不知道哪里出错了！

【问题讨论】：

你确定调用了 regionDidChangeAnimated 方法吗？因为这个方法告诉代理，地图视图显示的区域刚刚发生了变化。

您是否将您的 UIViewController 设置为 MKMapViewDelegate？ myMapView.delegate = self

是的...但无法获得所需的结果。 :(

【参考方案1】：

更改了 getCenterlocation 功能，它的工作正常！ `func getCenterLocation(for mapView: MKMapView) -> CLLocation

 let latitude=mapView.centerCoordinate.latitude
 let longitude=mapView.centerCoordinate.longitude
 return CLLocation(latitude:latitude, longitude:longitude)

func getCenterLocation(for myMapView: MKMapView) -> CLLocation

 let latitude=myMapView.centerCoordinate.latitude
 let longitude=myMapView.centerCoordinate.longitude
 return CLLocation(latitude:latitude, longitude:longitude)

`