Experienced Ios Developer for Secure Billing System Mobile App Integration

We are seeking a skilled iOS developer to create an exclusive iPhone application that will integrate with our existing web-based billing system. The current system is fully functional, developed in Java, and utilizes a MySQL database. The primary goal is to extend key functionalities to a mobile platform, providing our users with convenient access on the go. The application must support the following core features: User login, secure invoice issuance, generation of tax withholdings, and comprehensive viewing of previously issued invoices and withholdings. The mobile application will need to connect to our backend system. We prefer integration via existing APIs, but we are open to providing direct database access if deemed necessary for optimal performance and functionality. The ideal candidate will have a strong understanding of secure mobile development practices and experience with robust backend integration.