问题
I have an app with a tab bar controller embedded in a navigation controller. The app has 2 tabs, the first one(search) has a search bar implemented using the UISearchController. If I switch from this tab to the other tab(downloads) while I'm searching, to the other tab two things happen -
- The navigation bar in the second tab(downloads) disappears
- When i come back to the first tab(search), it shows a black screen
I have done all this using the storyboard.
this is my SearchViewController
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"
}
}
}
}
And this is my DownloadViewController
import UIKit
import QuickLook
class DownloadViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, QLPreviewControllerDataSource {
var items = [(name:String, url:String)]()
@IBOutlet weak var downloadsTable: UITableView!
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return items.count
}
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
print(items[indexPath.row].url)
// performSegueWithIdentifier("DocumentViewSegue", sender: items[indexPath.row].url)
let previewQL = QLPreviewController() // 4
previewQL.dataSource = self // 5
previewQL.currentPreviewItemIndex = indexPath.row // 6
showViewController(previewQL, sender: nil) // 7
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
if let cell = self.downloadsTable.dequeueReusableCellWithIdentifier("Download Cell") as? DownloadsTableCell {
cell.initCell(items[indexPath.row].name, detail: "", fileURL: items[indexPath.row].url)
return cell
}
return DownloadsTableCell()
}
func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
if editingStyle == UITableViewCellEditingStyle.Delete {
// let fileManager = NSFileManager.defaultManager()
//
// // Delete 'hello.swift' file
//
// do {
// try fileManager.removeItemAtPath(String(items[indexPath.row].url))
// }
// catch let error as NSError {
// print("Ooops! Something went wrong: \(error)")
// }
items.removeAtIndex(indexPath.row)
tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Automatic)
}
}
override func viewDidAppear(animated: Bool) {
items.removeAll()
let documentsUrl = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask).first!
// now lets get the directory contents (including folders)
do {
let directoryContents = try NSFileManager.defaultManager().contentsOfDirectoryAtURL(documentsUrl, includingPropertiesForKeys: nil, options: NSDirectoryEnumerationOptions())
// print(directoryContents)
for var file in directoryContents {
print(file.lastPathComponent)
print(file.absoluteURL)
// Save the data in the list as a tuple
self.items.append((file.lastPathComponent!, file.absoluteString))
}
} catch let error as NSError {
print(error.localizedDescription)
}
downloadsTable.reloadData()
}
// MARK: Preview
func numberOfPreviewItemsInPreviewController(controller: QLPreviewController) -> Int {
return items.count
}
func previewController(controller: QLPreviewController, previewItemAtIndex index: Int) -> QLPreviewItem {
return NSURL(string: items[index].url)!
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
override func viewWillAppear(animated: Bool) {
//do something
super.viewWillAppear(true)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
/*
// MARK: - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
// Get the new view controller using segue.destinationViewController.
// Pass the selected object to the new view controller.
}
*/
}
回答1:
Looks like the view that your UISearchController is attached to gets removed from the view hierarchy. You can think of the UISearchController as being presented modally when you start searching, and the definesPresentationContext property indicates which UIViewController would be the one to present it (more on this).
One of the ways to fix this would be reconfiguring your storyboard so that each tab has its own UINavigationController (in case you need it for both):
Instead of (what I suspect you have now):
And if you want to dismiss UISearchController when the tab switches, add this override to the ViewController:
override func viewWillDisappear(animated: Bool) {
super.viewWillDisappear(animated)
searchController.active = false
}
来源：https://stackoverflow.com/questions/37352057/getting-black-screen-on-using-tab-bar-while-searching-using-searchcontroller