UIWebView的高度问题

#pragma mark--

#pragma mark--方法1
- (void)webViewDidFinishLoad:(UIWebView *)webView
{
CGFloat webViewHeight = 0.0f;
if (webView.subviews.count > 0)
{
UIView *scrollerView = [webView.subviews objectAtIndex:0];//为什么要取第一个？
if (scrollerView.subviews.count > 0)
{
UIView *webDocView = scrollerView.subviews.lastObject;
if ([webDocView isKindOfClass:[NSClassFromString(@"UIWebDocumentView") class]])
{
webViewHeight = webDocView.frame.size.height;//获取文档的高度
webView.frame= webDocView.frame; //更新UIWebView 的高度
}
}
}
}

#pragma mark--
#pragma mark--方法2
- (void)webViewDidFinishLoad:(UIWebView *)webView
{
CGSize actualSize = [webView sizeThatFits:CGSizeZero];
CGRect newFrame = webView.frame;
newFrame.size.height = actualSize.height;
webView.frame = newFrame;
}

#pragma mark--
#pragma mark--方法3
- (void)webViewDidFinishLoad:(UIWebView *)webView
{
CGFloat webViewHeight=[webView.scrollView contentSize].height;
CGRect newFrame = webView.frame;
newFrame.size.height = webViewHeight;
webView.frame = newFrame;
}

- (void)webViewDidFinishLoad:(UIWebView *)webView
{
CGFloat height = [[webView stringByEvaluatingJavaScriptFromString:@"document.body.offsetHeight"] floatValue];
CGRect frame = webView.frame;
webView.frame = CGRectMake(frame.origin.x, frame.origin.y, frame.size.width, height);
}