title: Overlaying a UIView on a UIViewController
body: <p>I have an application with 6 view controllers all working fine and switching between each other. However, I want to overlay one of them with a UIView of graphics (Histogram or Line Chart, etc) which has a transparent background. How do I do this? Or, alternatively how do I switch from a UIViewController to a UIView  <em>and back</em>.  There is no interaction from the graphic (UIView) so I could use a modalview. What's the best way to achieve either?</p>