关闭 pdf 文件后故事板 segue 错误

Question

当我在完成后加载 pdf 文件时，当我按下完成时，它应该返回到上一个视图控制器，如果我愿意，我应该能够再次打开相同的 pdf 文件。但是当我尝试打开相同的pdf时，情况并非如此，我得到了这个错误

fileSystemRepresentationWithPath:]: nil 或空路径参数'

如果我将关闭功能更改为此 _ = self.navigationController?.popToRootViewController(animated: true)

它仍然可以工作。谁能帮我解决这个问题。这是我的代码。

类 showA3lamDa3waVC: UIViewController , UIWebViewDelegate,ReaderViewControllerDelegate{

var pdfbooks = UIWebView()
var nIndex:NSInteger!
var post: Post!
var db : DBHelperA3lam = DBHelperA3lam()
var book : a3lamDa3waModel?


@IBAction func backbtn(_ sender: Any) {

    if let navController = self.navigationController {
        navController.popViewController(animated: true)
    }
}


override func viewDidLoad() {
    super.viewDidLoad()

    var config : SwiftLoader.Config = SwiftLoader.Config()
    config.size = 150
    config.spinnerColor = .brown
    config.foregroundColor = .black
    config.foregroundAlpha = 0.5
    config.titleTextColor = .brown


    SwiftLoader.setConfig(config)


    if "" !=  book?.bookPath {
     //   self.activityIND.isHidden = true
     //   self.activityIND.stopAnimating()

        SwiftLoader.hide()
        UIApplication.shared.isNetworkActivityIndicatorVisible = false

        loadReader(filePaht: (book?.bookPath)!)
    } else {

        let documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]
        let strName = book?.id
        let filePath = "\(documentsPath)/"+strName!+".pdf"
        let fileManager = FileManager.default
    //    self.activityIND.startAnimating()

        SwiftLoader.show(title: "Loading...", animated: true)
        UIApplication.shared.isNetworkActivityIndicatorVisible = true


        if fileManager.fileExists(atPath: filePath) {
            //    self.loadFromUrl(path: filePath)
            loadReader(filePaht: (book?.bookPath)!)
            return;
        }


        let reference = FIRStorage.storage().reference(forURL: (self.book?.bookURL)!)
        reference.data(withMaxSize: 50 * 1024 * 1024) { (data, error) -> Void in
            if (error != nil) {

                print ("unable to download pdf file from Firebase Storage")

           //     self.activityIND.isHidden = false
           //     self.activityIND.startAnimating()
                SwiftLoader.show(title: "Loading...", animated: true)
                UIApplication.shared.isNetworkActivityIndicatorVisible = true


            } else {

                if ((try! data?.write(to: URL.init(fileURLWithPath: filePath, isDirectory: false))) != nil) {
                    //       self.loadFromUrl(path: filePath)
                    print ("pdf file is downloaded from Firebase Storage")
                    self.db.upDate(id: (self.book?.id)!, bookPath: filePath)
                 //   self.activityIND.isHidden = true
                    SwiftLoader.hide()
                    self.loadReader(filePaht: filePath)
                    UIApplication.shared.isNetworkActivityIndicatorVisible = false




                }
            }
        }

    }
}


func loadReader(filePaht : String)  {

    let document = ReaderDocument(filePath: filePaht, password: nil)
    if document != nil {
        let readerVC = ReaderViewController(readerDocument: document)
        readerVC?.delegate = self
        readerVC?.modalTransitionStyle = UIModalTransitionStyle.crossDissolve
        readerVC?.modalPresentationStyle = UIModalPresentationStyle.fullScreen
        self.navigationController?.pushViewController(readerVC!, animated: true)
    }

}

func dismiss(_ viewController: ReaderViewController!) {

   // _ = self.navigationController?.popToRootViewController(animated: true)

    if let a3lamDa3waVC = self.navigationController?.viewControllers[1] {

     _ = navigationController?.popToViewController(a3lamDa3waVC, animated: true)
          }
}


override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
}

}

这里是集合视图的代码

a3lamDa3waVC 类：UIViewController、UICollectionViewDelegate、UICollectionViewDataSource{

@IBOutlet weak var collectionView: UICollectionView!


var posts = [Post]()
let db : DBHelperA3lam = DBHelperA3lam()
var arrayBooks = [a3lamDa3waModel]()
var selectedIndexPath : IndexPath = IndexPath()
var post: Post!

override func viewDidLoad() {

    var config : SwiftLoader.Config = SwiftLoader.Config()
    config.size = 150
    config.spinnerColor = .brown
    config.foregroundColor = .black
    config.foregroundAlpha = 0.5
    config.titleTextColor = .brown


    SwiftLoader.setConfig(config)


    super.viewDidLoad()
 //   activityIndicator.isHidden = false

    SwiftLoader.show(title: "Loading...", animated: true)


    self.arrayBooks.removeAll()
    self.arrayBooks.append(contentsOf: self.db.fetchAll())
    self.collectionView.reloadData()
    DataService.ds.REF_POSTS.observe(.value, with: { (snapshot) in


        if let snapshot = snapshot.children.allObjects as? [FIRDataSnapshot] {

            for snap in snapshot {
                print ("SNAP: \(snap)")

                if let postDict = snap.value as? Dictionary<String, AnyObject>{
                    let key = snap.key
                    let post = Post(postKey: key , postData: postDict)
                    self.posts.append(post)
                    self.db.insertBook(id: postDict["id"] as! String, imgName: postDict["id"] as! String, imgPath: "", bookName: postDict["book_name"] as! String, bookPath: "", imageURL: postDict["image_path"] as! String, bookURL: postDict["book_path"] as! String, caption: "")




                }
            }
        } else {

        }
        self.arrayBooks.removeAll()
        self.arrayBooks.append(contentsOf: self.db.fetchAll())
        self.collectionView.reloadData()

    })


    collectionView.delegate = self
    collectionView.dataSource = self

}
func getFilePath(name : String) -> String {

    let documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]
    let filePath = documentsPath+"/"+name
    return filePath
}


@IBAction func backbtn(_ sender: Any) {
    if let navController = self.navigationController {
        navController.popViewController(animated: true)
    }
}



func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {


    return arrayBooks.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

    let book = arrayBooks[indexPath.item]
     SwiftLoader.hide()

    if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath)as? CollectionViewCellA3lamDa3wa {

        cell.initWithBook(book: book)

        return cell

    }else {
        return CollectionViewCellA3lamDa3wa()
    }


}

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    self.selectedIndexPath = indexPath
    self.performSegue(withIdentifier: "showImage", sender: self)
}

override func prepare(for segue: UIStoryboardSegue, sender: Any?)
{

    if segue.identifier == "showImage"
    {
        let vc = segue.destination as! showA3lamDa3waVC
        vc.book = self.arrayBooks[self.selectedIndexPath.row]

    }
}

}

Answer 1

为什么不使用popViewController(animated:) 方法？它必须回到前一个视图控制器 (Apple doc.)。