title: Why test and UITest and xctest file in Xcode project.
body: <p>Its a very basic thing that in Xcode once we create the application multiple files are created default. </p>
  
  <ol>
  <li>projectName.xctest </li>
  <li>projectNameTests.m</li>
  <li>projectNameUITests.m</li>
  <li>projectName.entitlements </li>
  </ol>
  
  <p>Can any one know the perps of these files and how and what can we use them. </p>
  
  <p>Thanks </p>