Saves an account to the Accounts database.
- iOS 5.0+
- macOS 10.8+
- UIKit for Mac 13.0+Beta
The account to save.
The handler to call when the operation is done. The handler is called on an arbitrary queue.
If the account type supports authentication and the account is not authenticated, the account server uses the account's credentials to authenticate it. If the authentication is successful, the account is saved; otherwise it is not saved.