title: UITableView, how to adjust the size of its header and footer?
body: <p>In auto-layout design, I choose universal size(600x600), and I drag a UITableView into the viewController within storyboard, this tableView occupy the whole horizontal space, and has 550 height. 
  I want to add a UIWebView (to load a local static html file.) as footer to the tableView, but after I add it, the webView can't show correctly( Just like webView has more horizontal space) . </p>
  
  <p>Its my code here: </p>
  
  <pre><code>- (void)viewDidLoad {
    [super viewDidLoad];
    [self loadHtml];
  }
  - (void) loadHtml {
  
    float height = 500; //maybe more , up to content of html
    _webview = [[UIWebView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width , height)];
    ...
   // load html fille content as html
   [ _webview loadHTMLString:html baseURL:nil];
   [self.table setTableFooterView: _webview];
  }
  </code></pre>
  
  <p>I debug the size of _webview, and found its width always is 600, even I change its value when init. How did I do.
  When use auto layout, that means we should not use fixed value, but how did init an UIView?</p>
  
  <p><strong>NOTE</strong> It's my fault, I do not add constraints for tableView.</p>