I can build this Application and Deliver you.
This App will be handed over to you along with all source code and is usable on the web as well.
Meaning, with one single code base users can log in to your Mobile Application from PC,Macs, iOS, Android and Windows tablets as native Apps too.
Do let me know if you have any additional queries and I will be more than willing to clarify those.
Also, if you have the design ready, I can incorporate that, in case you do not, I can suggest you the same for free.