Loader objects are used to load SWF files and graphics files into an application. The Loader class is a subclass of the DisplayObjectContainer class. A Loader object can contain only one child display object in its display list--the display object representing the SWF or graphic file that it loads. When you add a Loader object to the display list, as in the following code, you also add the loaded child display object to the display list once it loads:

var pictLdr:Loader = new Loader();
var pictURL:String = "banana.jpg"
var pictURLReq:URLRequest = new URLRequest(pictURL);
pictLdr.load(pictURLReq);
this.addChild(pictLdr);

Once the SWF file or image is loaded, you can move the loaded display object to another display object container, such as the container DisplayObjectContainer object in this example:

import flash.display.*;
import flash.net.URLRequest;
import flash.events.Event;
var container:Sprite = new Sprite();
addChild(container);
var pictLdr:Loader = new Loader();
var pictURL:String = "banana.jpg"
var pictURLReq:URLRequest = new URLRequest(pictURL);
pictLdr.load(pictURLReq);
pictLdr.contentLoaderInfo.addEventListener(Event.COMPLETE, imgLoaded); 
function imgLoaded(event:Event):void
{
    container.addChild(pictLdr.content); 
}