title: How do I embed a ViewController into a UIView programatically in Swift?
body: <p>I have a ViewController containing a UIView, and I want to embed a second ViewController programatically into the UIView. I'd presumed I needed to use <code>.addSubview()</code>, but it will not accept a UIViewController type.</p>
  
  <p>Any help would be great, thanks.</p>