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!!

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