         }
         
         // Get thumbnailImage
-        // self?.lastIndexInSession?[self.currentIndexSession!]!
-        //let lastIndexInThisSession: NSIndexPath = NSIndexPath(forRow: self.lastIndexInSession![self.currentIndexSession!]!, inSection: self.currentIndexSession!)
-        let lastIndexInThisSession: NSIndexPath = NSIndexPath(forRow: 0, inSection: 0)
-        
-        let nextThumbnail: UIImage? = self.getThumbnailImageAtIndexPath(lastIndexInThisSession)
-        if let image = nextThumbnail {
-            self.airImageView?.image = image
+        if let index = self.lastIndexInSession?[self.currentIndexSession!] {
+            let lastIndexInThisSession: NSIndexPath = NSIndexPath(forRow:index, inSection: self.currentIndexSession!)
+            let nextThumbnail: UIImage? = self.getThumbnailImageAtIndexPath(lastIndexInThisSession)
+            if let image = nextThumbnail {
+                self.airImageView?.image = image
+            }
         }
         
         UIView.animateWithDuration(0.2, delay: 0, options: UIViewAnimationOptions.CurveEaseInOut, animations: {[weak self]() -> Void in

        }
        
        // Get thumbnailImage
        //let lastIndexInThisSession: NSIndexPath = NSIndexPath(forRow: self.lastIndexInSession![self.currentIndexSession!]!, inSection: self.currentIndexSession!)
        let lastIndexInThisSession: NSIndexPath = NSIndexPath(forRow: 0, inSection: 0)

        
        let prevThumbnail: UIImage? = self.getThumbnailImageAtIndexPath(lastIndexInThisSession)
        if let prev = prevThumbnail {
            self.airImageView?.image = prevThumbnail
        }
        
        UIView.animateWithDuration(0.2, delay: 0, options: UIViewAnimationOptions.CurveEaseInOut, animations: {[weak self]() -> Void in

            _airImageView = newValue
        }
    }

    private var lastDeegreesRotateTransform: CGFloat?
    // pan for scroll
    private var panGestureRecognizer: UIPanGestureRecognizer?
