No known class method for selector 'credentialsWithUsername:password:register:'

  NSURL *authURL = [NSURL URLWithString:[NSString stringWithFormat:@"https://*********.cloud.realm.io"]];
   RLMSyncCredentials *credential = [RLMSyncCredentials credentialsWithUsername:@"*********"
                                                                        password:@"********"
                                                                        register:NO];

   
    [RLMSyncUser logInWithCredentials:credential
                        authServerURL:authURL
                         onCompletion:^(RLMSyncUser *user, NSError *error)

I can do credentialswithemail.but still not found.
/*******.m:35:4: Unknown type name ‘RLMSyncCredentials’; did you mean ‘RLMCredentials’?

All I want is sync.

What version of Realm are you using? Can I see a more complete compiler output please?