How to set the zoom level of a map view?

documentation still says to do the following:

myMapView.setLocation({
    latitude:37.337681, longitude:-122.038193, animate:true,
    latitudeDelta:0.04, longitudeDelta:0.04});

but that crashes my app since latitudeDelta is readonly? I tried setting a region but that didn't affect my zoom level. Can somebody explain to me how one can set the zoom level properly on a Map View?

I'd like to zoom in where before I had longitudeDelta and latitudeDelta set to 0.02. Unfortunately upgrading to the newest SDK since I created my app, breaks functionality.

Thanks for helping out!