title: ios - 'autorelease is unavailable' errors and 'ARC forbids explicit message send of autorelease' errors
body: <p>I had an app that was working just fine. And then I tried to embed the navigation controller into a tabbarcontroller and next thing I know I started getting these errors during compiling.</p>
  
  <p>Would anyone know why these happen? Did some setting get unchecked or checked by accident?</p>
  
  <p>Thanks,
  Alex</p>