如果我在Swift中选择我的位置，如何比较？

Question

我已经创建了一个包含mapView的应用程序。我在我的位置周围添加了几个注解。我希望当我点击一个注解时，能在一个标签中显示标题。

我这样做了，我把标题放在myLabel中，但是当我点击我的位置时，应用程序停止工作，我得到了错误。

(Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value)

这是我的代码。

import UIKit
import MapKit
import CoreLocation
import Foundation
class ViewControllermap: UIViewController, MKMapViewDelegate {
    @IBOutlet weak var mymap: MKMapView!
    @IBOutlet weak var viewaddress: UILabel!
    var selectedAnnotation: MKPointAnnotation?
    var locationManager: CLLocationManager = CLLocationManager()
    let regionInMeters:Double = 3000
    var previouslocation: CLLocation?
    var longitudeLocation:String = ""
    var latituseLocation:String  = ""
    override func viewDidLoad() {

        mymap.delegate = self
      //  checkLocationSevices()
        super.viewDidLoad()
        if let location = locationManager.location?.coordinate
               {
                   let region = MKCoordinateRegion.init(center: location, latitudinalMeters: regionInMeters, longitudinalMeters: regionInMeters)
                   mymap.setRegion(region, animated: true)
               }
        mymap.showsUserLocation = true
        let location = CLLocationCoordinate2DMake(35.1623, 33.3178)
        let annotation = MKPointAnnotation()
        annotation.coordinate = location
        annotation.title = "P1"
        annotation.subtitle = "28 oct street"
        mymap.addAnnotation(annotation)


        let location2 = CLLocationCoordinate2DMake(35.1658, 33.3147)
        let annotation2 = MKPointAnnotation()
        annotation2.coordinate = location2
        annotation2.title = "P2"
        annotation2.subtitle = " Makedonitissis 46, Nicosia 2417"
        mymap.addAnnotation(annotation2)

        let location3 = CLLocationCoordinate2DMake(35.1600, 33.3770)
        let annotation3 = MKPointAnnotation()
        annotation3.coordinate = location3
        annotation3.title = "P3"
        annotation3.subtitle = " Kallipoleos 75, Nicosia 1678"
        mymap.addAnnotation(annotation3)

        let location4 = CLLocationCoordinate2DMake(35.1602, 33.3390)
        let annotation4 = MKPointAnnotation()
        annotation4.coordinate = location4
        annotation4.title = "P4"
        annotation4.subtitle = "Diogenis Str 6 Nicosia CY, 2404"
        mymap.addAnnotation(annotation4)

        let location5 = CLLocationCoordinate2DMake(35.1673, 33.3277)
        let annotation5 = MKPointAnnotation()
        annotation5.coordinate = location5
        annotation5.title = "P5"
        annotation5.subtitle = "Neas Egkomis 4, Egkomi"
        mymap.addAnnotation(annotation5)

        let location6 = CLLocationCoordinate2DMake(35.1680, 33.3375)
        let annotation6 = MKPointAnnotation()
        annotation6.coordinate = location6
        annotation6.title = "P6"
        annotation6.subtitle = "Neas Egkomis 4, Egkomi"
        mymap.addAnnotation(annotation6)

        let location7 = CLLocationCoordinate2DMake(35.1460, 33.3357)
        let annotation7 = MKPointAnnotation()
        annotation7.coordinate = location7
        annotation7.title = "P7"
        annotation7.subtitle = "Neas Egkomis 4, Egkomi"
        mymap.addAnnotation(annotation7)

        let location8 = CLLocationCoordinate2DMake(35.1580, 33.3275)
        let annotation8 = MKPointAnnotation()
        annotation8.coordinate = location8
        annotation8.title = "P8"
        annotation8.subtitle = "Neas Egkomis 4, Egkomi"
        mymap.addAnnotation(annotation8)



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

    func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {
        if let annotationCoordinate = view.annotation?.coordinate {
        self.selectedAnnotation = view.annotation as? MKPointAnnotation

        viewaddress.text = "\(selectedAnnotation!.subtitle!)" as String
        }

    }
}

这个错误只是在我点击我的位置时发生，而其他注释的代码也在工作。

有谁知道我如何解决这个问题？

Answer 1

你的selectedAnotation或它的副标题是零......这就是为什么你得到这个崩溃......使用可选的链或可选的绑定，以避免这种情况。/未测试的代码

func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {
    if let annotationCoordinate = view.annotation?.coordinate {
    self.selectedAnnotation = view.annotation as? MKPointAnnotation

      if let annnotation = selectedAnnotation , let subTitle = annnotation.subTitle as? String {

           viewaddress.text = "\(subTitle)" 
      }
    }

}