Question

由于某些奇怪的原因，它会在我第一次尝试运行该程序时崩溃，但是如果我在模拟器仍在运行时再次运行它，它将运行正常。这是导致问题的代码片段。

class CityList : NSObject, CLLocationManagerDelegate {

// stored properties
var cities: [City]
var currentLocation: CLLocation? = nil
static let sharedInstance = CityList()
static let firstNotif = Notification.Name(rawValue: "test")
static let secondNotif = Notification.Name(rawValue: "test2")
let locationManager = CLLocationManager()

// initializers
override init () {
    cities = [
        City(name: "Medford", state: "Oregon", latitude: 42.3266667, longitude: -122.8744444),
        City(name: "Seattle", state: "Washington", latitude: 47.6063889, longitude: -122.3308333),
        City(name: "Grants, Pass", state: "Oregon", latitude: 42.4391667, longitude: -123.3272222),
        City(name: "Applegate", state: "Oregon", latitude: 42.2570662, longitude: -123.1683833),
        City(name: "San Francisco", state: "California", latitude: 37.775, longitude: -122.4183333)
    ]
    super.init()
    locationManager.delegate = self
    locationManager.requestWhenInUseAuthorization()// request user authorization
    locationManager.requestAlwaysAuthorization()
    locationManager.startUpdatingLocation()
    currentLocation = locationManager.location
    cities.append(City(name: "test", state: "test", location: currentLocation!))
}

Answer 1

您必须实现locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation])，CLLocationManagerDelegate才能正常工作

import CoreLocation

public class Location: NSObject, CLLocationManagerDelegate {
  private let manager = CLLocationManager()

  override convenience public init() {
    self.init()
    manager.desiredAccuracy = kCLLocationAccuracyThreeKilometers
    manager.delegate = self
    manager.requestWhenInUseAuthorization()
    manager.requestAlwaysAuthorization()
    manager.startUpdatingLocation()
  }

  public func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
    print("Error", error)
  }

  public func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    guard let location = locations.first else {
      return
    }

    print(location.coordinate.longitude)
    print(location.coordinate.latitude)
  }
}

CCLocation继续返回nil。使用单例

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