Hello,
I am developing an macOS app and planning to implement a cross-platform save feature. I have two questions regarding the App Store Review Guidelines and Game Center integration.
1. Requiring Game Center exclusively for an optional "Cross-Save" feature (Guideline 5.1.1 & HIG) in macOS
To comply with Guideline 5.1.1(v), we do not force users to sign in to Game Center upon app launch. Users can fully access the core features, play locally, and even use standard iCloud sync without any Game Center authentication. However, to use the specific, optional "Cross-Save" feature (which syncs data across different platforms via our proprietary backend), we intend to require Game Center login.
- Question: Is it acceptable to prompt for and require Game Center authentication only when the user explicitly tries to enable this specific cross-save feature?
2. Associating Game Center IDs with a proprietary backend account (Guidelines 4.5.3 & 4.5.5)
To facilitate cross-progression, our backend server plans to authenticate the user using Game Center's identity verification signature via fetchItems(forIdentityVerificationSignature:). Once authenticated, we want to link the user's Game Center ID (specifically, teamPlayerID or gamePlayerID) to our proprietary service account in our own database.
- Question: Guidelines 4.5.3 and 4.5.5 state that we should not share Player IDs with "any third party." Does storing and linking the Game Center ID to our own backend server account (strictly to manage our game's cross-saves) fall under this "third party" restriction, or is our proprietary backend considered a permitted, first-party use?
I want to ensure our implementation fully complies with Apple's privacy and user experience standards. Any insights would be greatly appreciated.
Thank you.