When use setState in Flutter? : <p>As newbie in flutter it's very confusing for me when use <code>setState</code> in <code>Flutter</code> application. In below code boolean <code>searching</code> and var <code>resBody</code> used inside <code>setState</code>. My question is why only <code>searching</code> and <code>resBody</code> inside setState? Why not others veriable?</p>

<pre><code>var resBody;
bool searching =  false,api_no_limit = false;
String user = null;

Future _getUser(String text) async{
setState(() {
  searching = true;
});
user = text;
_textController.clear();
String url = "https://api.github.com/users/"+text;
  var res = await http
      .get(Uri.encodeFull(url), headers: {"Accept": 
           "application/json"});
  setState(() {
    resBody = json.decode(res.body);
  });
}
</code></pre>
