How to Handle Canceled iOS In App Purchase Auto-Renewing Subscription

I'm wondering, if a user cancels a subscription and are trying to resubscribe am I supposed to present the management portal from within the App Store to this user and let them resubscribe from within the App Store or am I supposed to allow them to purchase a new subscription from within the App itself? It seems as if once a user has purchased the initial subscription from within the app itself Apple wants all other management to be done using the App Store.

I'm not exactly sure how this works and because I cannot access the 'Manage Subscriptions' portal for a sandbox App Store account I can't tell exactly how subscriptions are handled when they expire.

Thank you!

Solution

From the App Store subscription management page a user will be able to:

Change their auto-renew status
Upgrade or downgrade to a different subscription in the same group (e.g. change from a monthly to yearly subscription)
Resubscibe to an expired subscription

Paulw11’s comment is correct that you handle a re-subscribe exactly as a purchase in your app (the user won't receive a free trial if they had before). The purchase will go through as a normal subscription and it will be less confusing to your users.