iOS 如何计算UIWebView的ContentSize

首选要等UIWebView加载内容后，然后在它的回调方法里将webview的高度Height设置足够小，就设置为1吧，因为这样才能用
sizeThatFits才能计算出webview得内容大小

- (void)webViewDidFinishLoad:(UIWebView *)aWebView {    CGRect frame = aWebView.frame;    frame.size.height = 1;    aWebView.frame = frame;    CGSize fittingSize = [aWebView sizeThatFits:CGSizeZero];    frame.size = fittingSize;    aWebView.frame = frame;    NSLog(@"size: %f, %f", fittingSize.width, fittingSize.height);}