title: How to cancel all subscriptions and asynchronous task in the componentWillUnmount in React Native?
body: <p>I navigate between two screen success but It always shows warning me below:</p>
  <blockquote>
  <p>Warning: Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in the componentWillUnmount method</p>
  <p>in Alert (at AwesomeAlert.js:7)</p>
  <p>in AwesomeAlert (at LoadingDialog.js:7)</p>
  <p>in LoadingDialog (at LoginScreen.js:180)</p>
  </blockquote>
  <p>How to fix it?</p>