title: how to add wrap Layout in scroll view dynamically
body: <p>i want to add wrap layout elements in scroll view dynamically using java script.
  but when i try to add scroll view child it says, it is not a function.
  i want to know is it possible to achieve this or not. 
  one more thing is that i need to add layout by id i.e wrapId in below code. </p>
  
  <pre><code>&lt;Page xmlns="http://www.nativescript.org/tns.xsd" navigatingTo="onNavigatingTo"&gt;
      &lt;Page.actionBar&gt;
          &lt;ActionBar title="Wrap Layout" /&gt;
      &lt;/Page.actionBar&gt;
      &lt;ScrollView&gt;
          &lt;StackLayout id="wrapId"&gt;
  
          &lt;/StackLayout&gt;
      &lt;/ScrollView&gt;
  &lt;/Page&gt;
  </code></pre>
  
  <p><strong>this is my xml and below is the js</strong></p>
  
  <pre><code>const WrapLayout = require("tns-core-modules/ui/layouts/wrap-layout").WrapLayout;
  const StackLayout = require("tns-core-modules/ui/layouts/stack-layout").StackLayout;
  var ScrollView = require('ui/scroll-view').ScrollView;
  const Button = require("tns-core-modules/ui/button/").Button;
  
  exports.onNavigatingTo = function (args) {
    const page = args.object;
    var wrapId = page.getViewById("wrapId");
  
    const myWrap = new WrapLayout();
    const myScroll = new ScrollView();
  
    myScroll.orientation = "vertical";
  
    for (let i = 0; i &lt; 30; i++) {
      var button = `button${i}`;
      button = new Button();
      button.backgroundColor = "#0099CC";
      button.text = `${i}`;
      button.width = 150;
      button.height = 100;
      button.margin = 4;
      myWrap.addChild(button);
    }
  
    // myScroll.addChild(myWrap);
    page.content = myWrap;
  };
  </code></pre>