title: Use Size Classes in Xcode 6 beta
body: <p>Built a new project from scratch in Swift in Xcode 6 (Beta 1) and see File Inspector of Storyboard. There is <code>Use Size Classes</code> below <code>Use Auto Layout</code>. This is the screenshot of this.</p>
  
  <p><img src="https://i.stack.imgur.com/evscc.png" alt="enter image description here"></p>
  
  <p>1) What is <code>Use Size Classes</code>?</p>
  
  <p>2) Is it related with iPhone 6 screen size?</p>