Версия Swift:
FIRApp.configure()
// Creating a second app to create user without logging in
FIRApp.configure(withName: "CreatingUsersApp", options: FIRApp.defaultApp()!.options)
if let secondaryApp = FIRApp(named: "CreatingUsersApp") {
let secondaryAppAuth = FIRAuth(app: secondaryApp)
secondaryAppAuth?.createUser(...)
}