     
     var keyboardShowTimes = 0 {
         willSet {
-            println("set keyboardShowTimes \(newValue)")
+//            println("set keyboardShowTimes \(newValue)")
             
             if newValue == 0 {
                 if !self.isKeyboardVisible {

    func scrollToLastMessage() {
        
        if displayedMessagesRange.length > 0 {
            conversationCollectionView.scrollToItemAtIndexPath(NSIndexPath(forItem: displayedMessagesRange.length - 1, inSection: 0), atScrollPosition: UICollectionViewScrollPosition.Bottom, animated: false)
        
        }
    }

                
                UIView.animateWithDuration(0.2, delay: 0.0, options: UIViewAnimationOptions.CurveEaseInOut, animations: { () -> Void in
                    
                    if (useableSpace > 0) {
                        let contentToScroll = newMessagesTotalHeight - useableSpace
                        println("contentToScroll \(contentToScroll)")
                        self.conversationCollectionView.contentOffset.y += contentToScroll
                    } else {
                        if scrollToBottom {
                            
                            self.conversationCollectionView.contentOffset.y = self.conversationCollectionView.contentSize.height - self.conversationCollectionView.frame.size.height + keyboardAndToolBarHeight
                            
                        }else {
                            self.conversationCollectionView.contentOffset.y += newMessagesTotalHeight
                        }
                        
                    }
                    
                    }, completion: { (finished) -> Void in
                })
