功能 nextTapped 不会移动到下一个 pdf 页面

Question

function nextTapped 和 function previousTapped 显示此错误“使用未解析的标识符 'pdfView'；您的意思是 'PDFView'？”我想从函数 nextTapped 移动到下一个 pdf 页面，并且函数 previousTapped 在我显示 pdf 时移动到上一个 pdf 页面我想从 nextButton 移动到下一个 pdf 页面和 previousButton 移动到上一个 pdf 页面

import UIKit
import AVFoundation
import MobileCoreServices
import PDFKit
class RecorderViewController: UIViewController {
@IBOutlet var nextButton:UIButton!
@IBOutlet var previousButton:UIButton!  
override func viewDidLoad() {
    super.viewDidLoad()
nextButton.isHidden = true
previousButton.isHidden = true
}
@IBAction func `import`(_ sender: Any) {
    let documentPicker = UIDocumentPickerViewController(documentTypes: [kUTTypePDF as String], in: .import)
    documentPicker.delegate = self as? UIDocumentPickerDelegate
    documentPicker.allowsMultipleSelection = true
    present(documentPicker, animated: true, completion: nil)
}
override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
}
@IBAction func nextTapped(_ sender: Any) {
    pdfView.goToNextPage(sender)}
@IBAction func previousTapped(_ sender: Any) {
    pdfView.goToPreviousPage(sender)
}
extension RecorderViewController: UIDocumentPickerDelegate {
func documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentsAt urls: [URL]) {
    guard let selectedFileURL = urls.first else {
        return
    }
    /////////her to display PDF File
    let pdfView = PDFView()
    pdfView.frame = CGRect(x: 0, y: 160, width: 1024, height: 1139)
    pdfView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
    self.view.addSubview(pdfView)

    pdfView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor).isActive = true
    pdfView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor).isActive = true
    pdfView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true

    let thumbnailView = PDFThumbnailView()
    thumbnailView.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(thumbnailView)

    thumbnailView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor).isActive = true
    thumbnailView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor).isActive = true
    thumbnailView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor).isActive = true

    pdfView.bottomAnchor.constraint(equalTo: thumbnailView.topAnchor).isActive = true
    pdfView.heightAnchor.constraint(equalToConstant: 150)

    pdfView.displayMode = .singlePage
    // Fit content in PDFView.

    nextButton.isHidden = false
    previousButton.isHidden = false

    pdfView.autoScales = true
    pdfView.document = PDFDocument(url: selectedFileURL)


    let dir = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
    let sandboxFileURL = dir.appendingPathComponent(selectedFileURL.lastPathComponent)

    ///i need to ensure the file is saved
   if FileManager.default.fileExists(atPath: sandboxFileURL.path) {
        print("Already exists! Do nothing")
    }
    else {

        do {
            try FileManager.default.copyItem(at: selectedFileURL, to: sandboxFileURL)

            print("Copied file!")
        }
        catch {
            print("Error: \(error)")
        }
    }
}

}

Answer 1

在 Class 中定义您的 pdfView，而不是在 Extension 中，如下所示：

//Add PDF View Object here not in extension
    let pdfView = PDFView()

只需像这样稍微更新您的代码：

import UIKit
import AVFoundation
import MobileCoreServices
import PDFKit

class RecorderViewController: UIViewController {

    //Add PDF View Object here not in extension
    let pdfView = PDFView()

    @IBOutlet var nextButton:UIButton!
    @IBOutlet var previousButton:UIButton!

    override func viewDidLoad() {
        super.viewDidLoad()
        nextButton.isHidden = true
        previousButton.isHidden = true
    }

    @IBAction func `import`(_ sender: Any) {
        let documentPicker = UIDocumentPickerViewController(documentTypes: [kUTTypePDF as String], in: .import)
        documentPicker.delegate = self as? UIDocumentPickerDelegate
        documentPicker.allowsMultipleSelection = true
        present(documentPicker, animated: true, completion: nil)
    }

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

    @IBAction func nextTapped(_ sender: Any) {
        pdfView.goToNextPage(sender)
    }

    @IBAction func previousTapped(_ sender: Any) {
        pdfView.goToPreviousPage(sender)
    }

}

extension RecorderViewController: UIDocumentPickerDelegate {
    func documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentsAt urls: [URL]) {
        guard let selectedFileURL = urls.first else {
            return
        }
        /////////her to display PDF File

        pdfView.frame = CGRect(x: 0, y: 160, width: self.view.frame.size.width, height: self.view.frame.size.height - 160)
        pdfView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        self.view.addSubview(pdfView)

        pdfView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor).isActive = true
        pdfView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor).isActive = true
        pdfView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true

        let thumbnailView = PDFThumbnailView()
        thumbnailView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(thumbnailView)

        thumbnailView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor).isActive = true
        thumbnailView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor).isActive = true
        thumbnailView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor).isActive = true

        pdfView.bottomAnchor.constraint(equalTo: thumbnailView.topAnchor).isActive = true
        pdfView.heightAnchor.constraint(equalToConstant: 150)

        pdfView.displayMode = .singlePage
        // Fit content in PDFView.

        nextButton.isHidden = false
        previousButton.isHidden = false

        pdfView.autoScales = true
        pdfView.document = PDFDocument(url: selectedFileURL)


        let dir = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
        let sandboxFileURL = dir.appendingPathComponent(selectedFileURL.lastPathComponent)

        ///i need to ensure the file is saved
        if FileManager.default.fileExists(atPath: sandboxFileURL.path) {
            print("Already exists! Do nothing")
        }
        else {

            do {
                try FileManager.default.copyItem(at: selectedFileURL, to: sandboxFileURL)

                print("Copied file!")
            }
            catch {
                print("Error: \(error)")
            }
        }
}

希望这能解决您的问题。