 
     // MARK: Private
 
-    private func setConversaitonCollectionViewOriginalContentInsetBottom(bottom: CGFloat) {
+    private func setConversaitonCollectionViewContentInsetBottom(bottom: CGFloat) {
         var contentInset = conversationCollectionView.contentInset
         contentInset.bottom = bottom
         conversationCollectionView.contentInset = contentInset
     }
 
     private func setConversaitonCollectionViewOriginalContentInset() {
-        setConversaitonCollectionViewOriginalContentInsetBottom(messageToolbar.intrinsicContentSize().height)
+        setConversaitonCollectionViewContentInsetBottom(CGRectGetHeight(messageToolbar.bounds))
     }
 
     // MARK: Actions

                
                self.messageToolbarBottomConstraint.constant = keyboardHeight
                
                let keyboardAndToolBarHeight = keyboardHeight + self.messageToolbar.intrinsicContentSize().height
                
                let totleMessagesHeight = self.conversationCollectionView.contentSize.height + keyboardAndToolBarHeight + 64.0
                
                let visableMessageFieldHeight = self.conversationCollectionView.frame.size.height - (keyboardAndToolBarHeight + 64.0)
                
//                println("Content size is \(self.conversationCollectionView.contentSize.height) visableMessageFieldHeight \(visableMessageFieldHeight) totleMessagesHeight \(totleMessagesHeight) toolbar \(self.messageToolbar.intrinsicContentSize().height) keyboardHeight \(keyboardHeight) Navitation 64.0")
                
                let unvisibaleMessageHeight = self.conversationCollectionView.contentSize.height - visableMessageFieldHeight
                println("unvisibaleMessageHeight is \(unvisibaleMessageHeight)")

        // 初始时移动一次到底部
        if !conversationCollectionViewHasBeenMovedToBottomOnce {
            conversationCollectionViewHasBeenMovedToBottomOnce = true

            // 先调整一下初次的 contentInset
            setConversaitonCollectionViewOriginalContentInset()

            if messages.count > 0 {
                conversationCollectionView.scrollToItemAtIndexPath(NSIndexPath(forItem: Int(messages.count - 1), inSection: 0), atScrollPosition: UICollectionViewScrollPosition.Bottom, animated: false)
            }
