Objective c Firebase Twitter登录属性'；idToken'；在类型为'；FIRAuthCredential

我正试图通过遵循他们的文档来实现Firebase Twitter登录

 [self.provider getCredentialWithUIDelegate:nil
                                   completion:^(FIRAuthCredential *_Nullable credential, NSError *_Nullable error) {
        
          if (error) {
           // Handle error.
          }
          if (credential) {
            [[FIRAuth auth] signInWithCredential:credential
                                      completion:^(FIRAuthDataResult *_Nullable authResult, NSError *_Nullable error) {
              if (error) {
                // Handle error.
              }
                //Twitter OAuth ID token can be retrieved by calling:
                //authResult.credential.idToken
                NSLog(@"%@", authResult.credential.idToken)
                
            }];
          }
    }];

然而，当我尝试访问idToken时，我得到了这个错误

在类型为“FIRAuthCredential”的对象上找不到属性“idToken”

以下是文档：

我不确定他们是否在文档中输入了错误

 [self.provider getCredentialWithUIDelegate:nil
                                   completion:^(FIRAuthCredential *_Nullable credential, NSError *_Nullable error) {
        
          if (error) {
           // Handle error.
          }
          if (credential) {
            [[FIRAuth auth] signInWithCredential:credential
                                      completion:^(FIRAuthDataResult *_Nullable authResult, NSError *_Nullable error) {
              if (error) {
                // Handle error.
              }
                //Twitter OAuth ID token can be retrieved by calling:
                //authResult.credential.idToken
                NSLog(@"%@", authResult.credential.idToken)
                
            }];
          }
    }];

如果提供的代码不起作用，我如何访问idToken