---
title: "Changes in Game Center Sign-In"
description: "Changes in Game Center Sign-In"
published: "2023-02-02"
last_updated: "2023-02-02"
authors:
  - "Peter Friese (Developer Advocate)"
  - "Helen Zhou (Software Engineer)"
categories:
  - "Authentication"
canonical_url: "https://firebase.blog/posts/2023/01/firebase-auth-gamecenter"
---

# Changes in Game Center Sign-In

*Published February 2, 2023 by Peter Friese (Developer Advocate), Helen Zhou (Software Engineer)*

---
You can stop reading now if you don't use Game Center Sign-In with Firebase.

Apple has [deprecated](https://developer.apple.com/documentation/gamekit/gkplayer/1521127-playerid/) the `playerID` property of the `GKPlayer` object in favour of the new `teamPlayerID` and `gamePlayerID` properties. These two attributes have been introduced with the goal of increasing player privacy. To learn more about this, watch the [Game Center Player Identifiers WWDC session](https://developer.apple.com/videos/play/wwdc2019/615/?time=296).

Until now, Firebase Authentication has used `playerID` as the primary user identifier when users sign in to a game using [Game Center Sign-in](https://firebase.google.com/docs/auth/ios/game-center). This is changing.

To ensure that developers using Firebase Authentication are not affected by this deprecation, we are introducing `gamePlayerID` and `teamPlayerID` as optional fields to replace `playerID` in Firebase Authentication. These new fields, once passed with a valid ID, will be used as the primary user identifier for Game Center Sign-in. 

### Using the SDK

To utilise these new fields, developers will have to upgrade to the latest version of the Firebase SDK. Once you've upgraded to the new version of the SDK, requests will automatically use the new flow, and the user's identifiers for Game Center will automatically be updated to use the `gamePlayerID`.

When retrieving provider-specific information about a user, the `federatedId` field of the `ProviderUserInfo` will contain the `gamePlayerID` instead of the `playerID`.

### Using the REST API

When using the REST API directly, make sure to include both the `playerId` and the new fields (`teamPlayerID` and `gamePlayerID`) in calls to `signInWithGameCenter`. The new fields will be included in the response body, and will be encoded in any ID tokens for the Game Center provider.

Calls that include only the `playerId` will not be rejected, but it will not be possible to identify existing users that have already been migrated to the new SDK.

### Timeline

Expect the updated client SDKs and updated REST API to be available in early February 2023.

Upgrading the user identifier from the `playerID` to the new format is an irreversible process.

The [documentation](https://firebase.google.com/docs/auth/ios/game-center) will contain more details once the updated client SDKs are available.