Android & iOS App and Admin Panel Enhancements

I'm seeking a highly skilled mobile developer to help me with some modifications and bug fixes on my Android (Java) and iOS (Swift) apps, as well as an admin panel built with Django. The apps rely heavily on Google Fit and Apple Healthkit APIs and use SQLite as their database. The admin panel is hosted on a Digital Ocean server running Ubuntu.

Key Areas Needing Attention:
- Crashes: The app is experiencing crashes on Android. These need to be identified and rectified.
- UI/UX Issues: The user interface and overall user experience need to be improved. This includes fixing issues as well as making changes.
- API Issues: The apps are encountering data retrieval issues with the Google Fit and Apple Healthkit APIs. This needs to be addressed to ensure seamless data exchange.

New Functionalities to Implement:
- Push Notifications: Enhance user engagement by enabling push notifications.
- Social Media Integration: Implement social media links within the app.
- Various Marketplace Functionalities
- Referral System
- UX/UI Changes
- Configuration Tutorial
- Achievement System & User Profile
- Virtual Character Interface
- Ad Integration
- Disable Existing Tournament Functionality

I expect the ideal candidate to have:
- Proficiency in Java, Swift, Django, SQLite
- Prior experience in integrating Google Fit and Apple Healthkit APIs
- Track record of fixing crashes and improving UI/UX
- Strong understanding of push notifications
- Proven ability in developing admin panels
- Familiarity with hosting on Digital Ocean

Please provide a brief overview of your relevant experience when bidding.