iOS Developer for an appointment app

We have an appointment app that needs more development. All the tasks are (briefly)

-UI Bug fixes
-Firebase messaging implementation
-Onesignal implementation and testing
-Familiarity with Twilio video chat (implemented but needs further fixes)
-Familiarity with Stripe (implemented but needs further fixes)

I need a iOS developer who can complete these tasks. Connect with me for more detailed information.