title: UIView addSubview auto layout not working
body: <p>I created a UIView programatically and add NSLayoutConstraint to it and it works and then add it as a subView of view controller's view. Right now I need to remove this view from superview and some time later add it again. But the layout won't work any more if I add it again using <code>self.view addSubview</code>. How to make the layout works again?</p>