I'm trying to implement a simple google maps using swift.
The map should be displayed in a `UIView`.

Well, I follow the next steps:
I added a `UIView` element in my storyboard with the class `GMSMapView`

And declared in my `ViewController` with:

`@IBOutlet weak var mapView: GMSMapView!`

```
override func viewDidLoad() {
        super.viewDidLoad()

            let camera = GMSCameraPosition.camera(withLatitude: 51.050657, longitude: 10.649514, zoom: 5.5)
            let map = GMSMapView.map(withFrame: CGRect.zero, camera: camera)
            self.mapView = map

        }

```

And `GMSServices.provideAPIKey("xxx-xxx")` in my `AppDelegate.swift`.

Ok, those codes aren't returning any error, but in my screen it's displayed the Google text in colors and a gray background without the map.

What I'm doing wrong?