让UIWebView根据内容自动调整高度

1. 给他设置一个代理类  UIWebView needs a delegate to reset it's size accoreding to it's content.
2. 代理类中实现如下方法 Implish "- (void)webViewDidFinishLoad:(UIWebView *) webView" in the delegate:

- (void)webViewDidFinishLoad:(UIWebView *) webView
{
    CGSize actualSize = [webView sizeThatFits:CGSizeZero];

    CGRect newFrame = webView.frame;
    newFrame.size.height = actualSize.height;
    webView.frame = newFrame;
}

3. OK.