Loading local PDF, iOS, iPad2

Hi

I'm trying to make my application view local PDF on iPad. This pdf was downloaded from internet into app-storage dir.  Here is some code:

var f:File = new File(obj.url);

var webView = new StageWebView();

webView.stage=parent.stage;

webView.viewPort=new Rectangle(,20,103,960,640);

//this doesn't work

webView.loadUrl(f.url);

//.. but this works ok.

//webView.loadURL("http://www.adobe.com/devnet/flex/pdfs/getting_started_with_Flex3.pdf")

File url is correct:

"file:///var/mobile/Applications/5053796F-3E4A-41A5-AF05-A2F2D0E71791/Library/Application%20Support/..."

Target file exists.

But PDF document isn't shown.

Could you help me with this issue please?

Thanks in advance.