title: How to load dialog box automatically and dismiss in flutter?
body: <p>I used 
  <code>Future.delayed(Duration.zero, () =&gt; welcomeDialogBoxx(context));</code>
  in build, a method to load dialog box automatically but there is an issue with it, whenever I navigate through another screen the dialog box further open on that screen.
  Dunno why it is loading further after got dismissed.</p>
  
  <p>here is the method the defined for the dialog box</p>
  
  <pre class="lang-dart prettyprint-override"><code>welcomeDialogBoxx(BuildContext context) {
      return showDialog(
          context: context,
          builder: (BuildContext context) {
            return AlertDialog(
              .....
            );
          });
    }
  
  </code></pre>