Android and iOS application Developer

I am in need of an experienced mobile application developer to help create an e-commerce app for both Android and iOS. I have partially outlined the app's design guidelines but require someone who can provide expertise and provide high quality development to create a polished user experience. The app must be technically sound and provide users with the necessary features for them to utilize the e-commerce functionality. The goal of this project is to create an app that will allow customers to make purchases, track their orders, and have access to a variety of services that will enhance the shopping experience. The developer must have a good understanding of both platforms and any language that can be used to develop the app; in addition, must also be able to work with me to ensure the final product meets my expectations. I'm looking for someone that can bring their experience and knowledge to this project to help create a successful and user-friendly app.