title: Callback issue with getSteam iOS sdk
body: <p>I think something wrong with the iOS SDK of getStream. I m not getting any callback on following , unfollowing and checking if user is following someone.For all these three case callback is not coming. 
  Even in the sample app given by stream is not working for these case. 
  Below is the code from ProfileViewController from sample app.
  Rest of the sample app working fine.
  Url of the sample is : <a href="https://github.com/GetStream/swift-activity-feed" rel="nofollow noreferrer">https://github.com/GetStream/swift-activity-feed</a></p>
  
  <pre><code>User.current?.isFollow(toTarget: flatFeedPresenter.flatFeed.feedId) { [weak self] in
          button.isEnabled = true
  
          if let error = $2 {
              self?.showErrorAlert(error)
          } else {
              button.isSelected = $0
          }
      }
  </code></pre>