ios - 位置管理器 didUpdateLocations 未被调用

Question

由于某些原因 didUpdateLocations 没有被调用，即使我将委托(delegate)设置为 View Controller 。在 info.plist 中，我将键 Privacy - Location When In Use Usage Description 设置为描述。所以我不确定自己做错了什么？

import MapKit
import CoreLocation

class OptionsViewController: UIViewController, UITableViewDelegate, CLLocationManagerDelegate {
    override func viewDidLoad() {
          //Ask user for location
        locationManager = CLLocationManager()
        locationManager.requestWhenInUseAuthorization()

        //Use users current location if no starting point set
        if CLLocationManager.locationServicesEnabled() {
            let locationManager = CLLocationManager()
            locationManager.delegate = self
            locationManager.desiredAccuracy = kCLLocationAccuracyBest
            locationManager.startUpdatingLocation()
        }
    }

    override func viewDidAppear(_ animated: Bool) {
        locationManager = CLLocationManager()
        locationManager.requestWhenInUseAuthorization()
    }

    func locationManager(_ manager: CLLocationManager, didFailWithError error: Error){
        locationManager.stopUpdatingLocation()
        print(error)
    }

    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        print("Did update location called?")
        let locValue:CLLocationCoordinate2D = manager.location!.coordinate
        print("locations = \(locValue.latitude) \(locValue.longitude)")
    }
}

Answer 1

问题在这里:

  override func viewDidAppear(_ animated: Bool) {
      locationManager = CLLocationManager()
      locationManager.requestWhenInUseAuthorization()
  }

此方法将在 viewDidLoad 之后调用，但您稍后在 viewDidAppear 中新创建了一个 locationManager 并且没有将其委托(delegate)指向自身。这就是为什么不调用 delegate(self) 的方法的原因。

改进但不是最好的方法是:

class OptionsViewController: UIViewController, UITableViewDelegate, CLLocationManagerDelegate {

    let locationManager = CLLocationManager()

    override func viewDidLoad() {
        //Ask user for location
        locationManager.delegate = self
        locationManager.desiredAccuracy = kCLLocationAccuracyBest

        //Use users current location if no starting point set
        if CLLocationManager.locationServicesEnabled() {
            if CLLocationManager.authorizationStatus() == CLAuthorizationStatus.authorizedWhenInUse
              || CLLocationManager.authorizationStatus() == CLAuthorizationStatus.authorizedAlways {
                locationManager.startUpdatingLocation()
            }
            else{
                locationManager.requestWhenInUseAuthorization()
            }
        }
        else{
            //Alert user to open location service, bra bra bra here...
        }
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        //... nothing need to do for location here
    }

    public func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) {
        if status == CLAuthorizationStatus.authorizedWhenInUse
          || status == CLAuthorizationStatus.authorizedAlways {
            locationManager.startUpdatingLocation()
        }
        else{
            //other procedures when location service is not permitted.
        }
    }

    //......
}