I want to create a button where a user can cancel a auto-renewal subscription (or get redirected to App Store).
Is that possible without the user having to go through the whole purchase process first? If it is, how would you go about doing it?
December 2019
The correct URL is now https://apps.apple.com/account/subscriptions according to Apple's Handling Subscriptions Billing Documentation.
So just use:
UIApplication.shared.open(URL(string: "https://apps.apple.com/account/subscriptions")!)