I have an app with auto-renewable subscription and I want to add a free trial period.
I'm trying to use "introductory offer" feature, but can't figure out how to get it working.
I have configured a free trial introductory offer in itunes connect, but nothing changes when I try to buy the subscription from my app.
So my question is: Do I have to support this feature on my side (as described here https://developer.apple.com/documentation/storekit/in-app_purchase/implementing_subscription_offers_in_your_app?language=objc) with all that signature stuff? Or this is actually not needed in case of offering trial. I have seen some contradictory opinions in the internet. One is that free trial feature is simply not supported in sandbox environment.
