[Moru]

Not to play doomsday profet but: Apple does not want you to be able to use some other application to access data that apple is already having an application for. So expect to be shut down when apple finally realizes what your app is for.

[lylejohnson]

Unless I'm misunderstanding your point, you seem to be ignoring the numerous third-party calendar iOS apps that access and manipulate your calendar. I'm using one called Fantastical, but there are many others.

[shadesandcolour]

Fantastical uses EventKit. As do many of the other calendar apps.