UIRefarchControl下的UISearchController

Question

我尝试将UIRefreshControl和UISearchController放入UITableView。

当我下拉到refresh时效果很好，但首先加载UIRefreshControl is covered by the UISearchController：

这是我的代码：

override func viewDidLoad() {
    super.viewDidLoad()

    self.refreshControl = UIRefreshControl()
    self.refreshControl?.backgroundColor=UIColor.clearColor()
    self.refreshControl!.addTarget(self, action: #selector(SocialManTableViewController.refresh(_:)), forControlEvents: UIControlEvents.ValueChanged)
    self.refreshControl!.tintColor = UIColor(colorLiteralRed: 59/255, green: 89/255, blue: 152/255, alpha: 1)
    self.refreshControl!.beginRefreshing()


    searchController = UISearchController(searchResultsController: nil)
    searchController.searchBar.sizeToFit()
    searchController.searchBar.barTintColor = UIColor.clearColor()
    searchController.searchBar.backgroundImage = UIImage()
    searchController.searchBar.tintColor=UIColor.blackColor()
    tableView.setContentOffset(CGPoint(x: 0, y: searchController.searchBar.frame.size.height), animated: false)
    tableView.tableHeaderView = searchController.searchBar
    definesPresentationContext = true
    searchController.searchResultsUpdater = self
    searchController.dimsBackgroundDuringPresentation = false
}