swift – 为什么LocationManager多次调用startUpdatingLocation

import UIKit
import CoreLocation

class ViewController: UIViewController,CLLocationManagerDelegate
{

    let locationManager = CLLocationManager()

    override func viewDidLoad()
    {
        super.viewDidLoad()

        self.locationManager.delegate = self
        self.locationManager.desiredAccuracy = kCLLocationAccuracyBest
        self.locationManager.requestWhenInUseAuthorization()
        self.locationManager.startUpdatingLocation()
    }

    override func didReceiveMemoryWarning()
    {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func locationManager(manager: CLLocationManager,didUpdateLocations locations: [CLLocation]) {
        CLGeocoder().reverseGeocodeLocation(manager.location!,completionHandler: {(placemarks,error) -> Void in

            if (error != nil)
            {
                print("Error: " + error!.localizedDescription)
                return
            }

            if placemarks!.count > 0 {
                if let pm = placemarks?.first {
                    self.displayLocationInfo(pm)
                }
            }
            else
            {
                print("Error with the data.")
            }
        })
    }

    func displayLocationInfo(placemark: CLPlacemark)
    {

        self.locationManager.stopUpdatingLocation()
        print(placemark.locality)
        print(placemark.postalCode)
        print(placemark.administrativeArea)
        print(placemark.country)
    }

    func locationManager(manager: CLLocationManager,didFailWithError error: NSError)
    {
        print("Error: " + error.localizedDescription)
    }

}