iOS In-App pucrhase: Handle prorating of plan while switching

How can I handle In-App SaaS plan upgrade (from paid plan A -> paid plan B.) How do you handle pro-rating and switching of subscript开发者_如何学JAVAion?

There is a paid plan A for $9.99/month and a paid plan B for $19.99/month.

The user has a free account and then upgrades via an In-App subscription to Plan A. The user loves Plan A so much that they want to upgrade to Plan B two days later. How do you handle this with In-App purchases?

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You don't.

The Apple-supplied in-app purchasing system does not provide a way to pro-rate a purchase. There is no way to do a refund, and there is no way for a vendor (you) to do a cancellation.

Also be careful, if you implement plan A and plan B as separate subscriptions... a user who signs up for plan B after signing up for plan A will very likely be signed up for both. They will need to cancel their subscription to plan A.

In general, the in-app purchasing system is not well suited for tiered offerings such as you describe.

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Apple new subscription system https://developer.apple.com/app-store/subscriptions/ now provides downgrade/upgrade/crossgrade capabilities.