The iOS file/storage system is and remains a black box. For example, if I download a file from my server via the web component, I can't specify a fixed path. I see the result (the path) at the end, but I can't check whether the file exists either via the file manager or programmatically. The only option is to use a component that attempts to access the path (the file) and determine whether the file actually exists there. If the attempt fails, I have to download the file again and see that a new path is created.
This is one of the main reasons why I've currently paused development of my iOS apps. Since only 30MB is available for the aia (IPA), I have to download larger files in advance. After some time or after restarting the iOS device, the files/paths seem to disappear, so I have to start a complicated and time-consuming procedure before each restart of the app to ensure the existence of all files.