Implemented a working first draft of what I want.
RadialMenuButton that expands other sub buttons and you have to move towards them to activate the right one (à la Prismatic).
Code cleaning and using content/background views in RadialMenuButton (need to do the same for RadialMenuView)
Added an animation for the selection.
Added more examples with highlighting.
Added a UITabBarController to show the 2 examples.
Removed useless test code.