myLocationEnabled - 展开时意外发现 nil

Question

我只是想使用 GoogleMaps API 在我的 MapViewController 中获取用户位置。我到处环顾四周，无法弄清楚为什么我不断收到致命错误：在展开包装时意外发现 nil 并在此特定位置提供可选值。

这是我的代码：

class MapViewController: UIViewController {

    let locationManager = CLLocationManager()
    @IBOutlet weak var mapView: GMSMapView!

    override func viewDidLoad() {
        super.viewDidLoad()

        locationManager.delegate = self
        locationManager.requestWhenInUseAuthorization()

        let camera = GMSCameraPosition.cameraWithLatitude(-34.9290, longitude:138.6010, zoom:10)
        let mapView = GMSMapView.mapWithFrame(CGRectZero, camera:camera)
        mapView.mapType = kGMSTypeNormal
        print("Calling addMarker")
        // addMarker()
        self.view = mapView
        }

extension MapViewController: CLLocationManagerDelegate {
    func locationManager(manager: CLLocationManager, didChangeAuthorizationStatus status: CLAuthorizationStatus) {
        if status == .AuthorizedWhenInUse {
            locationManager.startUpdatingLocation()
            mapView.myLocationEnabled = true
            mapView.settings.myLocationButton = true
        }
    }

    func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        if let location = locations.first {
            mapView.camera = GMSCameraPosition(target: location.coordinate, zoom: 15, bearing: 0, viewingAngle: 0)
            locationManager.stopUpdatingLocation()
        }
    }
}

这是我收到错误的地方：

!(http://imgur.com/qxxf0SV)

我知道 mapView.myLocationEnabled 返回 nil 但不明白 why/how。

Answer 1

很可能是 mapView 为 nil，而不是 mapView.myLocationEnabled。当您遇到崩溃时，请尝试以下 lldb 命令：

po mapView

那会告诉你确切的。

didChangeAuthorizationStatus 委托可能正在后台调用或在视图完成之前调用。您应该将这些扩展程序移动到您的 AppDelegate 中。

myLocationEnabled - 展开时意外发现 nil

myLocationEnabled - Unexpectedly found nil while unwrapping

mkmapview

cllocationmanager

ios

swift