title: In Swift (tvOS) how do you change a UIButton's highlight and focus colors?
body: <p>So I have some buttons that I've added to a view through the Interface Builder and rather than using the system buttons I made them custom. I'm trying to figure out how to change characteristics, such as the text color and background color during different states (highlighted, focused, etc). </p>
  
  <p>It doesn't seem like I can do it through the IB so I'll probably make a subclass of UIButton and change them there, but I'm having trouble finding what properties to change. I don't see them explicitly mentioned in the documentation</p>