Hello I had been working on your question but I had resolved on Objective C, so I will post my answer and a translation to Swift
On DemoModelData
Init
JSQMessagesBubbleImageFactory *bubbleFactory = [[JSQMessagesBubbleImageFactory alloc] initWithBubbleImage:[UIImage imageNamed:@"bubbleMine"] capInsets:UIEdgeInsetsZero layoutDirection:UIUserInterfaceLayoutDirectionRightToLeft];
self.outgoingBubbleImageData = [bubbleFactory outgoingMessagesBubbleImageWithColor:[UIColor grayColor]];
Swift Translation
let bubbleFactory = JSQMessagesBubbleImageFactory(bubbleImage: UIImage(named: "bubbleMine")!, capInsets: UIEdgeInsetsZero, layoutDirection: .RightToLeft)
self.outgoingBubbleImageData = bubbleFactory.outgoingMessagesBubbleImageWithColor(UIColor.grayColor())
self.incomingBubbleImageData = bubbleFactory.outgoingMessagesBubbleImageWithColor(UIColor.jsq_messageBubbleGreenColor())
Note that the shape is what you get from this, not the color
I hope this helps you, for me works ok