应用（swift）无法显示核心位置授权提醒

Question

我正在按照'iOS Apprentice'中的教程编写一个快速的应用程序，在这一步，我想使用场景中的getButton来显示访问GPS的授权警报，但它不起作用。我查了一下代码并修改info.plist（添加了NSLocationWhenInUsageDescription）但仍无效。

import UIKit
import CoreLocation

class CurrentLocationViewController: UIViewController,CLLocationManagerDelegate {

let locationManager = CLLocationManager()

@IBOutlet weak var messageLabel:UILabel!
@IBOutlet weak var latitudeLabel:UILabel!
@IBOutlet weak var longitudeLabel:UILabel!
@IBOutlet weak var addressLabel:UILabel!
@IBOutlet weak var tagButton:UIButton!
@IBOutlet weak var getButton:UIButton!

@IBAction func getLocation() {
    let authStatus:CLAuthorizationStatus = CLLocationManager.authorizationStatus()
    if authStatus == .NotDetermined {
        locationManager.requestWhenInUseAuthorization()
        return
    }

    locationManager.delegate = self
    locationManager.desiredAccuracy = kCLLocationAccuracyNearestTenMeters
    locationManager.startUpdatingLocation()
}

// MARK: - CLLocationManagerDelegate
func locationManager(manager:CLLocationManager!,didFailWithError error:NSError!) {
    print("didFailWithError \(error)")
}

func locationManager(manager:CLLocationManager!,didUpdateLocations locations:[AnyObject]!) {
    let newLocation = locations.last as! CLLocation
    print("didUpdateLocations \(newLocation)")
}