Hey ericyee,
Looking at your requirements, it doesn't seem like it would be a difficult project. I'm actually working on another project right now that utilizes Foursquare, so I'm more than familiar with the API and it's really fresh in my mind. I've also just finished another project doing fixes for an iOS app (feel free to check out my reviews, you'll notice the review for that work), so that's no problem either.
Just let me know if you want and we can talk and discuss your requirements. I'll be more than happy to sign your NDA as well.
Regards,
Eric