Cast a loaded Flex Application to an Interface
Over at The Question Room (or @thequestionroom) the banditos received a bunch of tweet questions about a problem @gertjansmits was having when loading a Flex application with a SWFLoader and casting it to an interface.
They’ve called on my help to get the answer 
Download the application FXP (Flash Builder 4 project) or
Run the application (Right click and View Source)
My simple interface class, TestInterface, implements 3 functions, a simple getter/setter pair and a function called sayHello.
TestInterface.as
1 2 3 4 5 6 7 8 9 | package com.flexdaddy { public interface TestInterface { function get givenName():String function set givenName(str:String):void function sayHello():void; } } |
You first need to make sure the Application you are loading implements this interface. My root application tag looks like this:
LoadedApp.mxml
1 2 3 | <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" implements="com.flexdaddy.TestInterface" width="100%" height="100%"> |
And then in a Script block I make sure to implement all three functions specified above.
LoadedApp.mxml (LoadedApp.swf)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 | <?xml version="1.0" encoding="utf-8"?> <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" implements="com.flexdaddy.TestInterface" width="100%" height="100%" > <mx:Script> <![CDATA[ import mx.controls.Alert; private var _givenName:String; public function set givenName( str:String ):void { _givenName = str; } public function get givenName():String { return _givenName; } public function sayHello():void { mx.controls.Alert.show( "Hello " + givenName ); } ]]> </mx:Script> </mx:Application> |
Now when loading the LoadedApp application when using a SWFLoader in the main application we first need to do the following:
- Listen for a SWFLoader complete event
- Cast the SWFLoader content as a SystemManager
- Add an event listener on the loaded content for a FlexEvent.APPLICATION_COMPLETE
- When FlexEvent.APPLICATION_COMPLETE we can cast event.currentTarget.application to our Interface
This will make sense in the code below. You’ll also notice that after we cast the loaded Flex application to TestInterface we can directly call on any methods or properties implemented from the Interface. In this case I set the givenName and call the sayHello function.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 | <?xml version="1.0" encoding="utf-8"?> <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"> <mx:Script> <![CDATA[ import mx.events.FlexEvent; import mx.managers.SystemManager; import com.flexdaddy.TestInterface; private var myLoadedApp:TestInterface; protected function swfloaderComplete(event:Event):void { // the SWF Loader has complete but we need to wait for the // Flex application to load var loadedApp:SystemManager = event.target.content as SystemManager; loadedApp.addEventListener( FlexEvent.APPLICATION_COMPLETE, loadedAppComplete ); } protected function loadedAppComplete( event:FlexEvent ):void { // cast the loaded application to the Interface myLoadedApp = event.currentTarget.application as TestInterface; myLoadedApp.givenName = "Flex Daddy"; myLoadedApp.sayHello(); } ]]> </mx:Script> <mx:SWFLoader source="LoadedApp.swf" complete="swfloaderComplete(event)" /> </mx:Application> |
And that’s it!
Download the application FXP (Flash Builder 4 project) or
Run the application (Right click and View Source)
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