Programming Flex 3

Loading One Flex Application into Another Flex Application

Loading one Flex application into another Flex application is actually remarkably simple. All you need to do is create an SWFLoader instance and set the source property, as shown here:

<mx:SWFLoader source="application.swf" />

However, it gets slightly more challenging when you want to interact with the content you are loading. For example, if you want to call a public method defined in the loaded application, you must know two important things:

• What is the path to the loaded application relative to the SWFLoader used to load the application?

• When has the loaded application actually initialized?

The answers to these questions are as follows. When an SWFLoader loads a Flex application, the SWFLoader object’s content property provides a reference to the root of the loaded Flex application. As we’ve already discussed, that root is a SystemManager object. The SystemManager class defines an application property that references the Application object. However, it’s important to understand that the application property of a SystemManager object for a Flex application that has just loaded will be null because the loaded content will still be on its first frame, and the Application instance isn’t constructed until the second frame. This might seem to pose a problem, but there is a relatively elegant solution.

When an SWFLoader loads and initializes the content, it dispatches an init event. You should first handle the init event. This tells ...