Cross-Platform Dealer Auction App Development

I'm looking to develop a Dealer Auction Application for both Android and iOS platforms. The app should facilitate user registration and login, as well as provide a robust auction bidding system.

Key requirements include:
- User Roles: Admin, Dealer, and Buyer
- Secure user registration and login functionality
- Comprehensive auction bidding system

Ideal skills and experience:
- Proven experience in mobile app development for both Android and iOS
- Strong background in implementing secure user authentication
- Experience with auction systems and real-time bidding functionalities
- Familiarity with user role management and admin dashboards

Please provide examples of similar work done.