title: UIViewController SizeClass Compact and Regular in iOS8
body: <p>UiViewController sizeClass</p>
  
  <p>in Potrait - </p>
  
  <p>1) VerticalSizeClass - Regular
  2) RegularSizeClass - Compact</p>
  
  <p>in Landscape - 
  1) VerticalSizeClass - Compact
  2) RegularSizeClass - Compact</p>
  
  <p>why?? What is Regular and Compact exactly means?</p>