Try to look at controllers in codeigniter as your data glue. A controller retrieves data from clients, standardizes it and triggers the appropriate actions (redirect, triggering libraries, views, models and helpers while using the data provided.)
In your case just use a controller to retreive the data from your models or userinput. Then pass it to a library that creates the pdf. If the pdf creation is succesfull return true to let te controller know its a succes. Create a flashdata succes message and redirect to a page that outputs a view:
- User request: pdf/download
- Controller Pdf triggers the download method
- download triggers the models and pushes the data to a view
- The view with its data will be returned into a variable
- The $view variable will be pushed to a Pdf library
- trigger pdf create
- Pdf triggers pdf download (optional)
- Controller triggers redirect to pdf/overview