Could not get current location using Google Map API (GMSMapView) - ios

Question

I try to get the direction from current location to other point using Google Map API. Everything is OK when i input the origin point and destination point manually. But, when i try to set the origin point as current location, the location is null as the following code:
mainMap=[[GMSMapView alloc] initWithFrame:CGRectMake(0, 0, self.view.bounds.size.width, self.view.bounds.size.height)];
GMSCameraPosition *camera = [GMSCameraPosition cameraWithTarget:[mainMap.myLocation coordinate] zoom:13];
mainMap.camera=camera;
mainMap.myLocationEnabled=YES; // <---- The blue point appear on map: it's exactly my location
[self.view addSubview:mainMap];
//Get mylocation
CLLocation *myLocation = mainMap.myLocation; // <----- NULL
Is there any body know what is my problem here? Tks a lot

Answer 1

The thing is: Getting a location is asynchronous and how you do it is expect it to block till its there... which is not how it works
you have to add a KVO observer inn the map and observer myLocation.
Then when your observe method gets called, you get the myLocation.
(that's how the blue dot works too :))
- (void)viewDidLoad {
//...
[self.mapView addObserver:self forKeyPath:"myLocation" options:0 context:nil];
}
- (void)dealloc {
[_mapView removeObserver:self forKeyPath:#"myLocation"];
}
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
if([keyPath isEqualToString:#"myLocation"]) {
CLLocation *l = [object myLocation];
//...
}
}