While we do not have a specific developer to recommend, you might check out a service like Thumbtack where you can find a professional for just about any type of service:
Just look for “Mobile App Developers”.
There are other similar freelance services out there like Fiver “Pro”. The Pro version of this site is a collection of vetted developers with a proven track record.
Hopefully that gives you a place to start and other users will chime in with their recommendations as well!