Swift：谷歌地图代码抛出零例外

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Google Map检查     var locationManager：CLLocationManager！     var viewController：ViewController！ //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工作，直到我说回去，然后它在此行上抛出nil错误消息：

    viewController.locationRecieved(locationManager.location)

可能是什么原因？我可以看到地图上的图钉，虽然地图上没有显示任何图形，除了下面的谷歌徽标

Answer 1

如果您在视图（GMSMapView的子类）中没有看到地图图形，这是因为Google地图API密钥，可能您尚未在应用委托中设置它或未正确设置！

确保您已使用Google应用套件ID和您的帐户设置了正确的Google API密钥。你必须在app app中设置下面的代码，做didFinishLaunchingWithOptions函数：

import GoogleMaps

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

Answer 2

location上的CLLocationManager属性是可选的 - 意味着它可以是零。根据文档，如果没有检索过位置数据，那将是零。

您没有显示viewController.locationRecieved是如何定义的，但我的猜测是您已将CLLocation参数配置为隐式展开的可选项（即带有“！”）。将nil传递给这样的参数会导致崩溃。