title: Cannot use a C++ file in Xcode - Cannot Resolve Libs
body: <p>I am trying to figure out why XCode cannot resolve a C++ file I imported.</p>
  
  <ul>
  <li>I have changed the file extension to .mm</li>
  <li>I have added the .h file contents to the top of my file</li>
  <li>I have command line tools installed</li>
  </ul>
  
  <p>The code complete detects the algorithm library:</p>
  
  <p><img src="https://i.stack.imgur.com/0s6m9.png" alt="Code Complete Works"></p>
  
  <p>But when I try compile I get this:</p>
  
  <p><img src="https://i.stack.imgur.com/4MvNq.png" alt="Not working"></p>