Firebase 身份验证会话在 iOS 钥匙串中保留在用户设备上.卸载应用程序时，应用程序的钥匙串数据不会删除.

The Firebase authentication session is persisted on the user's device in the iOS keychain. The keychain data for the application is not removed when the application is uninstalled.

如果您希望手动清除数据，您可以将一些额外的元数据与您的应用程序一起存储并手动调用 FirebaseRef.unauth() 以清除持久会话.请参阅#4747404:卸载应用程序时删除钥匙串项供其他参考.

If you're looking to manually clear the data, you can store some additional metadata along with your application and manually call FirebaseRef.unauth() to clear the persisted session. See #4747404: Delete keychain items when an app is uninstalled for an additional reference.