Mobile app for study purpose

I am looking for a mobile app developer to create an app that is compatible with both iOS and Android. The primary function of the app will be to provide quizzes for study purposes. I am open to any subject for the course materials, so the ideal freelancer will have experience in creating educational apps with customizable content. The app should have a user-friendly interface, allow for progress tracking and provide feedback on quiz performance. Experience with integrating social sharing and in-app purchases is a plus.