title: react-native equivalent to native event calls like CALL_STATE_OFFHOOK in TelephonyManager
body: <p>I am learning react native and finished the <a href="https://facebook.github.io/react-native/docs/tutorial.html" rel="nofollow noreferrer">official react native tutorial</a></p>
  
  <p>What is not clear to me yet is, how to utilize the native features and implement native events like,</p>
  
  <ol>
  <li>Listening to an event whether a call has ended or not</li>
  <li>Opening up a camera and taking a picture</li>
  <li>Activating GPS and fetch co-ordinates
  ...etc</li>
  </ol>
  
  <p>I do not find any traces of these in the official tutorial link that i have posted earlier. Additionally, at the <a href="https://facebook.github.io/react-native/docs/more-resources.html" rel="nofollow noreferrer">end of the tutorial in this page</a> it says</p>
  
  <blockquote>
    <p>The folks who built the app for Facebook's F8 conference in 2016 also
    open-sourced the code and wrote up a detailed series of
    tutorials. This is useful if you want a more in-depth example
    that's more realistic than most sample apps out there.</p>
  </blockquote>
  
  <p>But not able to find examples there either., </p>
  
  <p>Kindly explain why and what am i missing here ?</p>