DOMDocument change when webframe loadrequest

In my webkit plugin, I can get DOMDocument from [webFrame DOMDocument] in the first time load the web that embed my plugin.

 webFrame = [[arguments objectForKey:WebPlugInContainerKey] webFrame];

   DOMDocument *dom = [webFrame DOMDocument];

But when the webframe load another url (that not embed my plugin)

 [webFrame loadRequest: myRequest];

   DOMDocument *dom1 = [webFr开发者_StackOverflow中文版ame DOMDocument];

it is error to access dom1!! I do not know which method to access DOMDocument with the webframe that loaded myRequest?? any help would be appreciated!!

you have to wait for the download to complete before calling domDocument by using a the delegate