斯威夫特：谷歌地图代码抛出零异常

Question

我有以下代码，它应该基本上检测位置（如果位置服务已打开），然后返回上一页并显示坐标（单击按钮时）。

@IBOutlet var mapView:GMSMapView!// 在 Storyboard 上添加谷歌地图检查 var locationManager：CLLocationManager！ var viewController : 视图控制器！ //保存前一个控制器的对象以返回位置

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view.
    locationManager = CLLocationManager() // Intialize the location manager
    locationManager.delegate = self

}


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

//Methos to change the MApType
@IBAction func changeMaptoEarthView()
{
    self.mapView.mapType = kGMSTypeSatellite
}

@IBAction func changeMaptoMapView()
{
    self.mapView.mapType = kGMSTypeNormal
}
//Method to get UserLocation
@IBAction func sendLocationtoPreviousView()
{
    viewController.locationRecieved(locationManager.location)
    self.performSegueWithIdentifier("backSegue", sender: nil)
}

@IBAction func addUserLocation() //Detect location click event
{
    if(CLLocationManager.authorizationStatus() == .AuthorizedWhenInUse) // If already have location access
    {
        locationManager.startUpdatingLocation()
    }
    else if (CLLocationManager.authorizationStatus() == .Denied)// If location access is denied in setting
    {
        UIAlertView(title: "Permission", message: "Please allow location services in setting", delegate: nil, cancelButtonTitle: "ok").show()
    }
    else
    {
        locationManager.requestWhenInUseAuthorization() // Ask user permission if permission not given
    }
}

//CLLocation Manager Delegate methoda
func locationManager(manager: CLLocationManager!, didChangeAuthorizationStatus status: CLAuthorizationStatus) {

    if status == .AuthorizedWhenInUse {

        locationManager.startUpdatingLocation()

    }
}


func locationManager(manager: CLLocationManager!, didUpdateLocations locations: [AnyObject]!) {
    if let location = locations.first as? CLLocation {

        self.mapView.clear() // clear all overlay on Map
        self.mapView.camera = GMSCameraPosition(target: location.coordinate, zoom: 15, bearing: 0, viewingAngle: 0)
        // Adding pin on Current location
        var marker = GMSMarker()
        marker.position = location.coordinate
        marker.snippet = "My Location"
        marker.appearAnimation = kGMSMarkerAnimationPop
        marker.map = mapView

        locationManager.stopUpdatingLocation()
    }
}

应用程序在模拟器中运行，直到我说返回，然后它在这一行抛出 nil 错误消息：

    viewController.locationRecieved(locationManager.location)

可能是什么原因？我可以在地图上看到图钉，虽然地图没有显示任何图形，除了下面的谷歌徽标

Answer 1

如果您在视图（GMSMapView 的子类）中看不到地图图形，这是因为 Google 地图 API 密钥，可能您尚未在应用程序委托中设置它或未正确设置它！

确保您已使用您的 app bundle id 和您在 google 中的帐户设置了正确的 google API 密钥。您必须在您的应用程序中设置以下代码删除，didFinishLaunchingWithOptions 功能：

import GoogleMaps

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
          GMSServices.provideAPIKey("your API Key")
}

Answer 2

CLLocationManager 上的 location 属性是 Optional - 这意味着它可以为 nil。根据文档，如果没有检索到任何位置数据，它将为零。

您没有显示viewController.locationRecieved 是如何定义的，但我猜您已将CLLocation 参数配置为隐式展开的可选参数（即，使用“！”）。将 nil 传递给这样的参数将导致崩溃。