UIWebView in multithread ViewController

Question

I have a UIWebView in a viewcontroller, which has two methods as below. The question is if I pop out(tap back on navigation bar) this controller before the second thread is

Answer 1

- (void)dealloc
{
    if(![NSThread isMainThread]) {
        [self performSelectorOnMainThread:@selector(dealloc) 
                               withObject:nil 
                            waitUntilDone:[NSThread isMainThread]];
        return;
    } 
    [super dealloc];
}