ActionScript: programmatically adding children to a `mx:ViewStack` - actionscript-3

Question

I have a Flex mx:ViewStack that have some Flex children, but I want to add more using ActionScript.
var o:MyCanvas = new MyCanvas;
o.id = 'modRipley';
viewStack.addChild(o);
o = new MyCanvas;
o.id = 'modNewt';
viewStack.addChild(o);
o = new MyCanvas;
o.id = 'modGorman';
viewStack.addChild(o);
Stepping through, I don't see any increase to the childDescriptors member (nor the _childDescriptors) and:
viewStack.getChildByName('modNewt');
just returns null.
I am using the Flex 3.5 SDK.

Answer 1

Instead of assigning o.id = 'modNewt'; use o.name = 'modNewt'; and try to access child by using viewStack.getChildByName('modNewt');. It should work.

Answer 2

Like my comment said, using addChild is correct, but your other code isn't useful. The childDescriptors is what the Flex framework uses to construct MXML children, so it's not expected to reflect dynamic changes made in ActionScript. And getChildByName requires that a child has a name value, while you have not given them a name, you've given them an id.
Typically, if I want to add view children dynamically, I do what the MXML compiler does with MXML children: create properties that will refer to the children when I create them. For example:
public class Example extends SomeMxmlComponentWithViewStack {
public var myCanvas1:MyCanvas;
public var myCanvas2:MyCanvas;
public var myCanvas3:MyCanvas;
override protected function createChildren():void {
super.createChildren(); // creates the MXML children
viewStack.addChild(myCanvas1 = new MyCanvas());
viewStack.addChild(myCanvas2 = new MyCanvas());
viewStack.addChild(myCanvas3 = new MyCanvas());
}
}
Now from any code you can refer to myCanvas1, myCanvas2 and myCanvas3. This is essentially what the MXML compiler does for you when you declare a component in MXML and give it an id.