title: Build and run Disabled in xcode
body: <p>There are some applications which shows <strong>Build and run</strong> icon disabled which stops me from running the application.It does not happen to all applications but on a few .  It mainly occurs to me in facebook applications and a few more applications.Can anybody have an idea what could be the problem ? I have tried everything from changing the build settings etc. but it does not work.</p>
  
  <p><img src="https://i.stack.imgur.com/K7Mjy.png" alt="enter image description here"></p>