I don't think Iwaku currently has the funds to develop its own standalone app.
In fact, I doubt that any roleplay community has the resources involved with doing something like that O_O
As is, the forum should be mobile-friendly so it should play somewhat nicely with your smartphone. I remember asking for Tapatalk integration a while ago (an app which aggregates forums and lets you browse them in a really clean way) but I think it was turned down for... some reason which I can't remember.