title: How to call method from another class in swift
body: <p>I have a viewcontroller class <code>ViewController</code> with collectionView. Also I have singleton class <code>FacebookManager</code> for fetching data from facebook.</p>
  
  <p>What I want to do is to run a method in facebook class and then call a method in ViewController to reload collectionView.</p>
  
  <p>I tried to make a reference to ViewController in Facebook manager by setting</p>
  
  <pre><code>class FacebookManager  {
     static let sharedInstance = FacebookManager()
     var vc:ViewController?
  }
  </code></pre>
  
  <p>Then setting in ViewController </p>
  
  <pre><code>class ViewController: {
     func viewDidLoad() {
        FacebookManager.sharedInstance.vc = self
     }
  }
  </code></pre>
  
  <p>And then calling in FacebookManager</p>
  
  <pre><code>func myMethod() {
     vc.collectionView.reloadData()
  }
  </code></pre>
  
  <p>But this doesn't work.</p>
  
  <p>How to do this properly?</p>