Details about the CrewLink App (by Harold Dijkstra) can be found here: CrewLink App (App Store)
It is designed to be a standalone App to locally store the roster as .pdf file. Calendar integration, like rostoics does it, is not featured. In the context of rostoics, CrewLink can be used to download and e-mail the roster to a specific address. This might sometimes be faster than accessing the company's NetLIne/Crew Crewlink web interface for downloading the roster. Such an e-mailed roster .pdf file is identical to the one downloaded directly via web interface.
Below some screenshots. Use the "Email" button on the second screenshot to send the roster .pdf file.