TableViewController中的UISearchBar在segue和更改旋转后向上移动

Question

我有master-detail应用程序，我使用UISearchController来过滤UITableViewController（master）中的单元格。我有问题在segue之后消失UISearchBar。重现问题的步骤：

1. 以纵向模式运行应用
2. 触摸SearchBar并键入搜索查询
3. 触摸TableView中的一个单元格并转到详细控制器
4. 在详细控制器中，将设备的方向更改为横向模式
5. 回想主人。现在，SearchBar部分隐藏在导航栏后面，即使在将导演定向回到肖像后也是如此。

我的主控制器的MWE：

import UIKit

class MasterViewController: UITableViewController, UISearchResultsUpdating {

    var data = ["First", "Second", "Third", "Fourth"]
    var searchController: UISearchController = UISearchController(searchResultsController: nil)

    override func viewDidLoad() {
        super.viewDidLoad()
        configureSearchController()
    }

    override func viewWillAppear(animated: Bool) {
        self.clearsSelectionOnViewWillAppear = self.splitViewController!.collapsed
        super.viewWillAppear(animated)
    }

    // MARK: - Search Controller

    private func configureSearchController() {
        searchController.searchResultsUpdater = self
        searchController.dimsBackgroundDuringPresentation = false
        searchController.hidesNavigationBarDuringPresentation = false
        searchController.searchBar.sizeToFit()

        self.definesPresentationContext = true
        self.tableView.tableHeaderView = searchController.searchBar
        self.tableView.contentOffset = CGPoint(x: 0, y: searchController.searchBar.frame.height)
    }

    func updateSearchResultsForSearchController(searchController: UISearchController) {
    }

    // MARK: - Segues

    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        if segue.identifier == "showDetail" {
            if let indexPath = self.tableView.indexPathForSelectedRow {
                let content = data[indexPath.row]
                let controller = (segue.destinationViewController as! UINavigationController).topViewController as! DetailViewController
                controller.text = content
                controller.navigationItem.leftBarButtonItem = self.splitViewController?.displayModeButtonItem()
                controller.navigationItem.leftItemsSupplementBackButton = true
            }
        }
    }

    // MARK: - Table View

    override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
        return 1
    }

    override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return data.count
    }

    override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
         let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath)

        let content = data[indexPath.row]
        cell.textLabel!.text = content
        return cell
    }

}

截图：