I use a service called elance.com. It lets you receive live bids and communicate with providers before selecting. The reason I use elance over others is because a lot of domestic providers are on elance (significant price difference though).
Just post your project, require they are located domestic, verify that their dev team is actually located in us.
Review their project management system as well for communication.
Or... you can hire someone to deal with communicating with the outsourced company.
If price is an is issue, depending on what your app does, there are new technologies that allow web developers (not just programers) to build apps such as Titanium and Appcelerator. If this is ok it drastically lowers prices as you are using a different skill set. I can verify for that since I am writing apps in Appcelerator and I do not have the normal apple Xcode experience.