Mobile Exam Testing App

I'm looking for an experienced mobile app developer to create an exam testing application for multiple choice questions. The app needs to be compatible with both iOS and Android platforms.

Key Features:
- Timer for each question
- Instant feedback after each question
- Review of answers at the end

Ideal Skills and Experience:
- Proficient in both iOS and Android development
- Experience with timer and feedback integration in mobile apps
- Strong UI/UX design skills for a smooth user experience

Please provide portfolios and relevant work experience.