title: Unrecognized selector sent to instance when using UIPanGesture
body: <p>Hi I am trying to add UIPanGestureRecognizer to UIImageView (in my case, it's an emoji). All other UIGestureRecognizers such as long press, rotation, and pinch work well. However, it gives me an error: unrecognized selector sent to instance when I add UIPanGestureRecognizer. I've spent a day trying to figure out the reason but failed to fix it. Please help! Thanks in advance. </p>
  
  <p>This is a function where I added UIGestureRecognizer to sticker </p>
  
  <pre><code>  func emojiInsert(imageName: String) {
  
      deleteButtonHides()
  
      let stickerView: UIImageView = UIImageView(frame: CGRectMake(backgroundImage.frame.width/2 - 50, backgroundImage.frame.height/2 - 50, stickerSize, stickerSize))
      stickerView.image = UIImage(named: imageName)
      stickerView.userInteractionEnabled = true
      stickerView.accessibilityIdentifier = "sticker"
  
      let deleteStickerButton: UIImageView = UIImageView(frame: CGRectMake(stickerView.frame.width - 5 - stickerView.frame.width/3, 5, stickerView.frame.width/3, stickerView.frame.height/3))
      deleteStickerButton.image = UIImage(named: "button_back")
      deleteStickerButton.accessibilityIdentifier = "delete"
      deleteStickerButton.userInteractionEnabled = true
      deleteStickerButton.alpha = 0
      deleteStickerButton.addGestureRecognizer(UITapGestureRecognizer(target: self, action: "deleteButtonTouches:"))
      stickerView.addSubview(deleteStickerButton)
  
  
      stickerView.addGestureRecognizer(UIPinchGestureRecognizer(target: self, action: "handlePinch:"))
      stickerView.addGestureRecognizer(UIRotationGestureRecognizer(target: self, action: "handleRotate:"))
      stickerView.addGestureRecognizer(UILongPressGestureRecognizer(target: self, action: "handleLongPress:"))
      stickerView.addGestureRecognizer(UIPanGestureRecognizer(target: self, action: "handlePan"))
  
      print("emojiInsert : \(imageName)")
  
      backgroundImage.addSubview(stickerView)
  }
  </code></pre>
  
  <p>Below are call back functions I added in the end of the view.swift. I used touchesbegan and touchesMoved to drag an emoji but emoji moved in weird way after rotation. So now I am trying to use UIPanGesture to drag an emoji.   </p>
  
  <pre><code>    @IBAction func handlePinch(recognizer : UIPinchGestureRecognizer) {
      if(deleteMode) {
          return
      }
      print("handlePinch \(recognizer.scale)")
  
      if let view = recognizer.view {
          view.transform = CGAffineTransformScale(view.transform,
              recognizer.scale, recognizer.scale)
          recognizer.scale = 1
      }
  }
  
  @IBAction func handleRotate(recognizer : UIRotationGestureRecognizer) {
      if(deleteMode) {
          return
      }
      if let view = recognizer.view {
          view.transform = CGAffineTransformRotate(view.transform, recognizer.rotation)
          recognizer.rotation = 0
      }
  }
  
  
  @IBAction func handlePan(recognizer:UIPanGestureRecognizer) {
      if(deleteMode) {
          return
      }
  
      let translation = recognizer.translationInView(self.view)
      if let view = recognizer.view {
          view.center = CGPoint(x:view.center.x + translation.x,
              y:view.center.y + translation.y)
      }
      recognizer.setTranslation(CGPointZero, inView: self.view)
  }
  
  
  @IBAction func handleLongPress(recognizer: UILongPressGestureRecognizer) {
      if(recognizer.state == UIGestureRecognizerState.Began) {
          if(!deleteMode) {
              print("LongPress - Delete Shows")
              for (_, stickers) in self.backgroundImage.subviews.enumerate() {
                  for (_, deleteButtons) in stickers.subviews.enumerate() {
                      if let delete:UIImageView = deleteButtons as? UIImageView{
                          if(delete.accessibilityIdentifier == "delete") {
                              delete.alpha = 1
                          }
                      }
                  }
              }
              deleteMode = true
          } else {
              deleteButtonHides()
          }
      }
  }
  </code></pre>
  
  <p>Again, please help! Thanks in advance. </p>