UIScrollView contentInset vs viewport padding

Question

I know about the contentInset on UIScrollView, however I'm trying to achieve something slightly different: I want to have a "viewport" on the scrollview: essentially have all the content scroll within the scrollview but at all times have a blank padding on all sides.

In CSS terms, I want to achieve {height: 300px; padding: 10px; overflow: scroll;}

Is this possible and, if yes, how would I do that?