思路:
1.将webView放入tableViewCell上面(contentView)
[cell.contentView addSubview:_webView];
2.在-(void)webViewDidFinishLoad:(UIWebView *)webView 设置 webView高度
-(void)webViewDidFinishLoad:(UIWebView *)webView
{
//获取到webview的高度
CGFloat height = [[self.webView stringByEvaluatingJavaScriptFromString:@"document.body.offsetHeight"] floatValue];
self.webView.frame = CGRectMake(self.webView.frame.origin.x,self.webView.frame.origin.y, SCREENWIDTH, height);
[self.tableView reloadData];
}