_WebTryThreadLock error

I am facing an error while开发者_StackOverflow中文版 manipulation the UIWebView in ipad application. in that I have to fill the UIWebview with the HTML string and though the content is coming from the APi so I have to implement the process under Thread. Below is the error message :

bool _WebTryThreadLock(bool), 0xb2aa410: Tried to obtain the web lock from a thread other than the main thread or the web thread. This may be a result of calling to UIKit from a secondary thread. Crashing now...

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you are doing some graphical changes in secondary thread .. you must do all the graphical changes in your main thread. check you thread code.