Hire an experienced developer with modern sensibilities.
I have 5 years experience in creating iOS apps. The bulk of my programming is in Objective-C. With the onset of Apple's Swift language, it's important you hire a developer with knowledge of the latest in software development.
My Objective-C skills will allow me to support any of your legacy apps. Swift skills allow me to create new apps in a new language that is already extremely popular. This also will future-proof your app in terms of code support.
Below are some of my apps currently available in the App Store.