Does [UIWebView loadRequest] block the thread?

I've read up on UIWebView and can't find a spe开发者_JAVA百科cific answer to whether or not it can block a thread when loadRequest is called (like NSURL can). I've heard that there is a specific UIWebView thread that all UIWebView's try to load using (and as a result that thread will be blocked with a slow load), but will there be any effect on the main thread (or the thread that makes the request)?

It seems like it doesn't, but I just wanted to confirm.

As far as I can tell, it does not. However, it will block any other UIWebViews that are also loading requests.