Preload external swf before play

Question

i have a project i am working on...but for some reason the solution i went with is not satisfying my instructor......
so....here is my new code ( which is incorrect but i cant figure out how to arrange the preloader at the end )
var Xpos:Number=0;
var Ypos:Number=0;
var swf:MovieClip;
var bgloader:Loader = new Loader();
var bgURL
if(page==1){
bgURL=new URLRequest("pages/home.swf");
else if(page==2){
bgURL=new URLRequest("pages/about.swf");
else if(page==3){
bgURL=new URLRequest("pages/projects.swf");
else if(page==4){
bgURL=new URLRequest("pages/experimental.swf");
else if(page==5){
bgURL=new URLRequest("pages/contact.swf");
bgloader.load(bgURL);
bgloader.x=Xpos;
bgloader.y=Ypos;
bg.addChild(bgloader);
stop();
var percent:Number = bgURL.bytesTotal;
if(percent==100){
gotoAndPlay("start");
first off, i dont even know if what i am being asked to do is possible...but, what i am being requested to do is obviously load in the external swf BUT, the external swf cannot play until the MAIN swf is directed to "start"......
i have done this numerous times in as1 and 2....but back then things were totally written different and if you do it the same way you run into migration issues....
i thought this was solved already, but my instructor will not accept the method of using an event to be dispatched in the external SWF to tell the main swf when to play "start"....im not sure if there is any other way to do this?
he wants the external swf to contain NO code other than what is necessary for its internal functions....
everything is to be coded in the MAIN swf.....
so im trying to use bytesTotal, and the percent==100 is just a number i threw in for example purposes.....i am just not figuring this out....
any help is greatly appreciated

Answer 1

From what I could gather based on your description, your instructor wants you to start playing when external swf is loaded completely.
If my understanding is correct, what you need to do conceptually is:
1. Instantiate Loader
2. Add event listeners that you are interested in.
3. Execute code corresponding to these listeners in their corresponding handler functions.
As for No 2 - Usually there are at least 3 events that are of interest when dealing with Loaders:
1. Event.COMPLETE - dispatched when entire target is loaded
2. ProgressEvent.PROGRESS - dispatched when a new bytes packet arrives.
3. IOErrorEvent.IO_ERROR - dispatched when something goes wrong with loading (say, wrong url, etc.)
In your particular case it is supposed to be something like this (may not work because you did not describe what is the point of different swfs loading and how it affects entire application). SEE COMMENTS:
stop();
var swf:MovieClip;
// always specify datatype
var bgURL:URLRequest;
if(page == 1) {
     bgURL = new URLRequest("pages/home.swf");
else if (page == 2) {
     bgURL = new URLRequest("pages/about.swf");
else if (page == 3) {
     bgURL = new URLRequest("pages/projects.swf");
else if (page == 4) {
     bgURL = new URLRequest("pages/experimental.swf");
else if (page == 5) {
     bgURL = new URLRequest("pages/contact.swf");
var bgloader:Loader = new Loader();
configureListeners();
// now you are ready to load
bgloader.load(bgURL);
* Adds listeners.
function configureListeners():void {
     // NOTE!!! Listeners are added to contentLoaderInfo - not Loader itself
     bgloader.contentLoaderInfo.addEventListener(Event.COMPLETE, onLoadComplete);
     bgloader.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS, onProgress);
     bgloader.contentLoaderInfo.addEventListener(IOErrorEvent.IO_ERROR, onLoadError);
* Removes listeners.
function removeListeners():void {
     bgloader.contentLoaderInfo.removeEventListener(Event.COMPLETE, onLoadComplete);
     bgloader.contentLoaderInfo.removeEventListener(ProgressEvent.PROGRESS, onProgress);
     bgloader.contentLoaderInfo.removeEventListener(IOErrorEvent.IO_ERROR, onLoadError);
function onLoadComplete(e:Event):void
     // depeneding on the situation
     // you may want to add loaded swf
     // but before if swf exists - you need to remove it
     if (swf && this.contains(swf)) {
          removeChild(swf);
          swf = null;
     swf = bgloader.content as MovieClip;
     addChild(swf);
     // now play
     this.gotToAndPlay("start");
     // dont't forget to remove listeners
     removeListeners();
function onLoadError(e:IOErrorEvent):void
     // deal with the error
function onProgress(e:ProgressEvent):void
     // here you update preloader if you have one
     trace("Progress", e.bytesLoaded, e.bytesTotal);
On a side note, the way you deal with instnatiating URLRequests is not the most efficient or scalable. A better approach would be to keep them in an array and call by index. Note, conditionals are gone.
var bgList:Array = [
          "pages/home.swf",
          "pages/about.swf",
          "pages/projects.swf",
          "pages/experimental.swf",
          "pages/contact.swf"];
var bgURL:URLRequest = new URLRequest(bgList[page]);