title: Login with Twitter on iOS
body: <p>I have a problem with twitter login on iOS. If the user has account set in Settings application, I get the following error:</p>
  
  <blockquote>
    <p>[TwitterKit] did encounter error with message "User's system account
    credentials are invalid.": Error Domain=TWTRLogInErrorDomain Code=7
    "The system account credentials are no longer valid and will need to
    be updated in the Settings app." UserInfo={NSLocalizedDescription=The
    system account credentials are no longer valid and will need to be
    updated in the Settings app., NSLocalizedRecoverySuggestion=The user
    has been prompted to visit the Settings app.}</p>
  </blockquote>
  
  <p>And the credentials are valid, I double check that.
  If there are no account in Settings app, my login goes as expected. 
  The method I call is:</p>
  
  <pre><code>Twitter.sharedInstance().logInWithCompletion {(session, error) -&gt; Void in
  </code></pre>