title: Can't select item in UICollectionView programmatically
body: <p>I'm trying to set a default item when the view is loaded this way:</p>
  
  <pre><code>override func viewDidLoad() {
     super.viewDidLoad()
  
     self.collectionView.delegate = self
     self.collectionView.dataSource = self
     self.collectionView.allowsSelection = true
     self.collectionView.allowsMultipleSelection = true
  
  }
  </code></pre>
  
  <p>I'm trying to select an item in the <code>viewDidAppear</code> method:</p>
  
  <pre><code>override func viewDidAppear(_ animated: Bool) {
      DispatchQueue.main.async(execute: {
          self.collectionView.selectItem(at: IndexPath(item: 0, section: 0), animated: true, scrollPosition: UICollectionViewScrollPosition.bottom)
      })
  }
  </code></pre>
  
  <p>But the <code>didSelectItemAt</code> method is not fired like I need.    </p>
  
  <pre><code>func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath){
     //some config
  }
  </code></pre>
  
  <p>Am I forgetting something?</p>