This behavior manages the interactivity between a title, anywhere in a UIScrollView and the title of a UINavigationBar. The behavior is defined so as the title subview scrolls under the title, the Nav Bar's title will translate into place.
This behavior is accomplished by leveraging the UINavigationBar().titleVerticalPositionAdjustment, allowing the title to play nicely with other UINavigationItems, (since it is using the normal navigationItem.title.)
override func viewDidLoad() {
super.viewDidLoad()
navigationItem.setTitle("Title Transition")
let behavior = NavTitleTransitionBehavior(scrollView: scrollView, titleView: titleLabel)
addBehaviors([behavior])
}