objective-c - 百度地圖定位所獲得的經緯度是0

Question

用百度地圖api定位，拿到的經緯度一直是0，程式碼如下

BMKLocationService *locationService = [[BMKLocationService alloc]init];
locationService.delegate = self;
[locationService startUserLocationService];
BMKUserLocation *location = locationService.userLocation;