iOS App Twilio Invite System Re-Integration

I have an iOS application that needs the Twilio-based invite system re-implemented. This feature was previously part of the app but was removed. I need you to reintegrate this functionality and troubleshoot any related issues that may have arisen since its removal.

Key Language & Frameworks:
- Objective C
- Native App & UIKit

Potential Additional Work:
- API integration
- Core PHP website modifications

I can provide the original specification document for the invite system if required.