Mobile App Enhancement for iOS and Android

I'm looking for an experienced developer to enhance an existing mobile app that's currently available on both iOS and Android platforms.

Key Requirements:
- Improve user interface and user experience (UI/UX)
- Optimize performance and speed
- Fix any existing bugs and issues
- Add new features based on user feedback

Ideal Skills and Experience:
- Proven experience in mobile app development for both iOS and Android
- Strong UI/UX design skills
- Proficient in debugging and performance optimization
- Familiarity with user feedback integration

Please provide examples of similar work done and any relevant qualifications.