ios - Tab Bar and UISearchController giving black screen

Question

I have two scenes which can be accessed through a tab bar, on scene 1 there is a search bar. the problem that I am facing is that while searching if I switch to the downloads tab -

1. The navigation bar disappears.
2. When I come back to the search tab, it gives me a black screen.

This is screen 1 while searching -

Now when I click on the downloads tab, the navigation bar disappears.

Here is the view controller for the first screen -

import UIKit
import Alamofire
import SwiftyJSON

class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource, UISearchResultsUpdating, UISearchBarDelegate{

    //MARK: Variables
    var papers = [Paper]()
    var filteredPapers = [Paper]()
    let searchController = UISearchController(searchResultsController: nil)

    // MARK: Outlets
    @IBOutlet weak var activityIndicator: UIActivityIndicatorView!
    @IBOutlet var table: UITableView!
    @IBOutlet weak var loadingMessageLabel: UILabel!
    @IBOutlet weak var retryButton: UIButton!

    //MARK: Actions
    @IBAction func retryButton(sender: UIButton) {
        self.loadingMessageLabel.hidden = false
        self.loadingMessageLabel.text = "While the satellite moves into position..."
        self.activityIndicator.hidden = false
        self.activityIndicator.startAnimating()
        self.retryButton.hidden = true
        self.getPapersData()

    }

    // MARK: Table View

    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        // If in searching mode, then return the number of results else return the total number
//        if searchController.active && searchController.searchBar.text != "" {
        if searchController.active {
            return filteredPapers.count
        }
        return papers.count
    }

    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

        let paper: Paper

//        if searchController.active && searchController.searchBar.text != "" {
        if searchController.active {
            paper = filteredPapers[indexPath.row]
        } else {
            paper = papers[indexPath.row]
        }

        if let cell = self.table.dequeueReusableCellWithIdentifier("Cell") as? PapersTableCell {

            cell.initCell(paper.name, detail: paper.detail)
            print(cell)
            return cell
        }

        return PapersTableCell()

    }

    func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
    }

    func tableView(tableView: UITableView, editActionsForRowAtIndexPath indexPath: NSIndexPath) -> [UITableViewRowAction]? {


        let downloadButton = UITableViewRowAction(style: .Normal, title: "Download") { action, index in

            var url = String(self.papers[indexPath.row].url)
            url = url.stringByReplacingOccurrencesOfString(" ", withString: "%20")
            print(url)
            let destination = Alamofire.Request.suggestedDownloadDestination(directory: .DocumentDirectory, domain: .UserDomainMask)

            // Spinner in cell

            //            var selectCell = self.table.cellForRowAtIndexPath(indexPath) as? PapersTableCell
            //            selectCell!.downloadSpinner.hidden = false

            // Dismiss the download button
            self.table.editing = false

            Alamofire.download(.GET, url, destination: destination).response { _, _, _, error in
                if let error = error {
                    print("Failed with error: (error)")
                } else {
                    print("Downloaded file successfully")
                }
                //                selectCell?.downloadSpinner.hidden = true
            }

        }

        downloadButton.backgroundColor = UIColor(red:0.30, green:0.85, blue:0.39, alpha:1.0)


        return [downloadButton]

    }

    func tableView(tableView: UITableView, canEditRowAtIndexPath indexPath: NSIndexPath) -> Bool {
        // the cells you would like the actions to appear needs to be editable
        return true
    }

    func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
        // you need to implement this method too or you can't swipe to display the actions
    }

    // MARK: Search

    func filterContentForSearchText(searchText: String, scope: String = "All") {
        filteredPapers = papers.filter { paper in
            let categoryMatch = (scope == "All") || (paper.exam == scope)
            return  categoryMatch && paper.name.lowercaseString.containsString(searchText.lowercaseString)
        }

        table.reloadData()
    }

    func updateSearchResultsForSearchController(searchController: UISearchController) {
        let searchBar = searchController.searchBar
        let scope = searchBar.scopeButtonTitles![searchBar.selectedScopeButtonIndex]
        filterContentForSearchText(searchController.searchBar.text!, scope: scope)

    }

    func searchBar(searchBar: UISearchBar, selectedScopeButtonIndexDidChange selectedScope: Int) {
        filterContentForSearchText(searchBar.text!, scope: searchBar.scopeButtonTitles![selectedScope])
    }

    // MARK: Defaults

    override func viewDidLoad() {
        super.viewDidLoad()

        self.getPapersData()

        searchController.searchResultsUpdater = self
        searchController.dimsBackgroundDuringPresentation = false
        definesPresentationContext = true
        table.tableHeaderView = searchController.searchBar
        searchController.searchBar.scopeButtonTitles = ["All", "ST1", "ST2", "PUT", "UT"]
        searchController.searchBar.delegate = self
        activityIndicator.startAnimating()


    }

    override func viewWillDisappear(animated: Bool) {
//        if searchController.active {
            self.searchController.resignFirstResponder()
//        }
    }




    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    // MARK: API call

    func getPapersData(){
        Alamofire.request(.GET, "http://silive.in/bytepad/rest/api/paper/getallpapers?query=")
            .responseJSON { response in

                self.activityIndicator.stopAnimating()
                self.activityIndicator.hidden = true

                // If the network works fine
                if response.result.isFailure != true {

                    self.loadingMessageLabel.hidden = true
                    self.table.hidden = false
                    //print(response.result)   // result of response serialization

                    let json = JSON(response.result.value!)

                    for item in json {
                        // Split the title on the . to remove the extention
                        let title = item.1["Title"].string!.characters.split(".").map(String.init)[0]
                        let category = item.1["ExamCategory"].string
                        let url = item.1["URL"].string
                        let detail = item.1["PaperCategory"].string

                        let paper = Paper(name: title, exam: category!, url: url!, detail: detail!)
                        self.papers.append(paper)

                    }
                    self.table.reloadData()

                }
                    // If the network fails
                else {
                    self.retryButton.hidden = false
                    self.loadingMessageLabel.text = "Check your internet connectivity"
                }

        }
    }


}

Answer 1

I had this problem in iOS12 and fixed it by setting definesPresentationContext to true for the viewcontroller hosting the search controller.

self.definesPresentationContext = true