Cross-Platform E-commerce App Development

I'm looking to develop an e-commerce app available on both iOS and Android platforms. The app should include:

User Authentication and Profiles
Product Search and Categorization
Payment Gateway Integration

Ideal candidates should have experience in:
- Mobile app development for both iOS and Android
- E-commerce platforms and features
- Secure payment integration
- User authentication systems

Please provide examples of similar work done and your approach to this project.