title: "Simulator in use" error message shown even after simultor is not running
body: <p>Whenever I try to run an application from Xcode it displays an error message:</p>
  
  <p><img src="https://i.stack.imgur.com/yjTlw.png" alt="Simulator in use"></p>
  
  <p>This happens even though the simulator is not running. I force quit the simulator process from Activity Monitor, but it shows that message again and again. </p>
  
  <p>If I quit and reopen Xcode it will work without error, but is there any solution other than closing Xcode?</p>
  
  <p><strong>Specification:</strong></p>
  
  <p>Most of answer showing me that you have to quit Xcode or restart Xcode. If there is a scenario when you are a middle of complex situation (like undo and redo code). In this situation if you close Xcode you are not able to undo the last modified code (Not talking about SVN commit). <strong><em>So i would like to know how to resolve it with out closing Xcode.</em></strong></p>
  
  <p>I'm running Xcode 5.1.1 (5B1008) on OS X 10.9.2</p>