something to think about...if you go off paying someone to develop an iOS app for you and it goes well, then you are gonna want something that works on other Android, etc. as well as a traditional web browser (possibly - making this statement not knowing what you are building). So you will need to get someone to build that. Now you have two code bases, two technologies and potentially multiple developers to deal with.
Why not just make a web app that is a responsive app, which will work on anything. You get single code base to deal with and it will work on any device that supports a web browser.
If you ask someone "can you build me a good iOS app", someone who can build it will certainly do that, but just trying to think about the bigger picture here...
Just a thought.
My caveat in the above is that I am assuming when someone says "mobile app", they mean native OS app.