iOS app rejected due to cookies without asking permission

Question

My app was recently rejected for App Store release with the following reason:

We noticed your app accesses web content you own where you collect cookies. Cookies may be used to track users, but you do not use App Tracking Transparency to request the user's permission before collecting data used to track.

The last part is correct: I do not apply App Tracking Transparency.

The first part is surprising:

• I do not explicitly access cookies by HTTPCookieStorage
• I show a terms-of-use webpage which is included in the app. It does not access any cookies. It has links to external sites that do, but I only navigate to these by switching to safari (using UIApplication.shared.open(...))

So: How do I figure out how/when cookies are accessed by my app, which makes apple require App Tracking Transparency?

Answer 1

I ended up asking Apple about the haps, and the reply stated the following:

we still find that your app indicates the collection of cookies on launch

After a bit back-and-forth, I removed some text in the bundled terms-of-use webpage - something copy-pasted from the website supporting the app, that indeed indicated collection of cookies... Completely irrelevant for the app.

That did the trick, and the app is approved.