 
     private func addAttachment(bubble: BubbleView) {
         assert(focusedBubble != nil)
-        let attachment = UIAttachmentBehavior.limitAttachmentWithItem(bubble, offsetFromCenter: UIOffsetZero, attachedToItem: focusedBubble!, offsetFromCenter: UIOffsetZero)
+        let attachment = UIAttachmentBehavior(item: bubble, attachedToItem: focusedBubble!)
         attachment.length = 120
         relatedAttachments[bubble] = attachment
         animator.addBehavior(attachment)
+        collisionBehavior.addItem(bubble)
     }
 
     private func removeAttachment(bubble: BubbleView) {

    private func removeBubble(bubble: BubbleView) {
        tapRecognizers.removeValueForKey(bubble)
        removeBehaviors(bubble)
        bubble.removeFromSuperview()
        indexToBubble.removeValueForKey(bubble.index!)
        bubble.index = nil
    }

            let newFocused = self.dataSource!.configureBubble(bubbleIndex)
            newFocused.index = bubbleIndex
            // We have to add it to the hiearchy
            newFocused.frame = CGRect(origin: view.center, size: CGSize(width: 100.0, height: 100.0))
            addBubble(newFocused)
            configureFocused(newFocused)
        }
