title: How to run `npm react-native run-ios` after upgrading mac os and upgrading xcode?
body: <p>I picked up a react-native project from 2018.  I was able to get the app to work in a simulator by typing <code>npm install; npx react-native run-ios</code> on a 2012 mac mini that had Xcode 9.0 installed.</p>
  <p>However, the iPhone 11 was not available from the list of simulators.  I read that I needed Xcode 11+ to get iPhone 11 simulator.  So i upgraded my mac mini from OS 10.13 to OS 10.15, then I upgrade Xcode to version 12.0.</p>
  <p>I loaded up the new Xcode and entered my Apple ID.  I then went to terminal and typed <code>npx react-native run-ios</code>, but I got the error:</p>
  <pre><code>`instruments` is now deprecated in favor of 'xcrun xctrace' (see `man xctrace` for more information on its replacement)
  
  Could not find iPhone 6 simulator
  </code></pre>
  <p>So then I ran the command <code>rm -rf node_modules; npm install;</code>, but then I got the error:</p>
  <pre><code>npm ERR! error: pathspec 'master' did not match any file(s) known to git
  </code></pre>
  <p>And trying to run <code>npx react-native run-ios</code> gives the error:</p>
  <pre><code>Command `run-ios` unrecognized. Make sure that you have run `npm install` and that you are inside a react-native project.
  </code></pre>
  <p>How do you make <code>npx react-native run-ios</code> to work?</p>