iOS App / Swift - create text file in another applications iCloud folder

I want to have an app that is able to create a note in my obsidian fault, which is in an iCloud folder of the obsidian application.

I thought at first that it is not possible to do that, but the app 'Actions for Obsidian' is somehow able to achieve this and I want to recreate the creation of a note with it.

Here is a link: https://actions.work/actions-for-obsidian