适用于 iOS 的 Google 地图 API myLocationEnabled 无法正常工作

我正在尝试使用 Google Maps API，但在获取用户位置时遇到问题。观察到的值似乎永远不会改变，因为observeValueForKeyPath 从未被调用。
注意：我正在运行 Xcode 6-Beta 5 和 iOS 8 beta（代码在 Swift 中）

override func viewDidLoad() {
    super.viewDidLoad()
    var camera:GMSCameraPosition? = nil
    mapView_ = GMSMapView.mapWithFrame(CGRectZero, camera:camera);
    mapView_!.addObserver(self, forKeyPath: "myLocation", options: NSKeyValueObservingOptions.fromRaw(0x01)!, context: nil);
    camera = GMSCameraPosition.cameraWithTarget(mapView_!.myLocation.coordinate, zoom: 6);
    mapView_!.camera = camera;


    self.view = mapView_;
    dispatch_async(dispatch_get_main_queue(), {
        mapView_!.myLocationEnabled = true;
        });

}
override func observeValueForKeyPath(keyPath: String!, ofObject object: AnyObject!, change: [NSObject : AnyObject]!, context: UnsafeMutablePointer<()>) {
    if (keyPath == "myLocation" && object.isKindOfClass(GMSMapView)) {
        mapView_!.animateToCameraPosition(GMSCameraPosition.cameraWithTarget(mapView_!.myLocation.coordinate, zoom: 6));
    }

}

截至目前，Google Maps iOS SDK 尚未更新为支持 iOS 8。因此，为了使用位置功能，您需要自行进行 iOS 8 位置授权。

您可以通过实例化来做到这一点CLLocationManager对象并执行-requestWhenInUseAuthorization or -requestAlwaysAuthorization关于这一点。您需要在设置之前执行此操作myLocationEnabled to YES.

请务必在您的文件中包含必要的密钥Info.plist文件。如果您想使用始终授权（如下面的代码示例所示），请提供NSLocationAlwaysUsageDescription，或者如果您想在使用时授权，NSLocationWhenInUseUsageDescription。其中之一是必需的，如果您不提供，位置功能将无法工作。

这是 Obj-C 中的示例。抱歉，我还没有掌握所有 Swift 的最新内容。 :)

// Rather than setting -myLocationEnabled to YES directly,
// call this method:

- (void)enableMyLocation
{
    CLAuthorizationStatus status = [CLLocationManager authorizationStatus];

    if (status == kCLAuthorizationStatusNotDetermined)
        [self requestLocationAuthorization];
    else if (status == kCLAuthorizationStatusDenied || status == kCLAuthorizationStatusRestricted)
        return; // we weren't allowed to show the user's location so don't enable
    else
        [self.view setMyLocationEnabled:YES];
}

// Ask the CLLocationManager for location authorization,
// and be sure to retain the manager somewhere on the class

- (void)requestLocationAuthorization
{
    _locationAuthorizationManager = [[CLLocationManager alloc] init];
    _locationAuthorizationManager.delegate = self;

    [_locationAuthorizationManager requestAlwaysAuthorization];
}

// Handle the authorization callback. This is usually
// called on a background thread so go back to main.

- (void)locationManager:(CLLocationManager *)manager didChangeAuthorizationStatus:(CLAuthorizationStatus)status
{
    if (status != kCLAuthorizationStatusNotDetermined) {
        [self performSelectorOnMainThread:@selector(enableMyLocation) withObject:nil waitUntilDone:[NSThread isMainThread]];

        _locationAuthorizationManager.delegate = nil;
        _locationAuthorizationManager = nil;
    }
}