title: Selector in swift3
body: <p>Why doesn't this work in swift 3 ? It crashes at runtime saying: </p>
  
  <blockquote>
    <p>'-[my_app_name.displayOtherAppsCtrl tap:]: unrecognized selector sent
    to instance 0x17eceb70'</p>
  </blockquote>
  
  <pre><code>    override func viewDidLoad() {
      super.viewDidLoad()
  
      // Uncomment the following line to preserve selection between presentations
      // self.clearsSelectionOnViewWillAppear = false
  
      // Register cell classes
      //self.collectionView!.register(ImageCell.self, forCellWithReuseIdentifier: reuseIdentifier)
  
      // Do any additional setup after loading the view.
  
    let lpgr = UITapGestureRecognizer(target: self, action: Selector("tap:"))
      lpgr.delegate = self
      collectionView?.addGestureRecognizer(lpgr)
  }
  
  func tap(gestureReconizer: UITapGestureRecognizer) {
  if gestureReconizer.state != UIGestureRecognizerState.ended {
    return
  }
  
  let p = gestureReconizer.location(in: self.collectionView)
  let indexPath = self.collectionView?.indexPathForItem(at: p)
  
  if let index = indexPath {
    //var cell = self.collectionView?.cellForItem(at: index)
    // do stuff with your cell, for example print the indexPath
    print(index.row)
  } else {
    print("Could not find index path")
  }
  }
  </code></pre>