Swift和Firebase：检测已撤销的令牌

Question

我想知道客户端（ios）是如何通知撤销令牌的，因为Google在本指南中说：

如何检测（在客户端设备上）令牌被撤销并采取相应行动（重新验证或注销）？

响应客户端上的令牌撤销

如果通过Admin SDK撤销令牌，则会通知客户端撤销，并且用户需要重新进行身份验证或退出：

GOOGLE的例子：

function onIdTokenRevocation() {
  // For an email/password user. Prompt the user for the password again.
    let password = prompt('Please provide your password for reauthentication');
    let credential = firebase.auth.EmailAuthProvider.credential(
    firebase.auth().currentUser.email, password);
    firebase.auth().currentUser.reauthenticateWithCredential(credential)
    .then(result => {
      // User successfully reauthenticated. New ID tokens should be valid.
    })
    .catch(error => {
      // An error occurred.
    });
}