如何在 Swift 5 中选择文件的屏幕上创建一个取消按钮？

Question

我正在使用 UIDocumentBrowser 来检索文件。但我无法在导航栏中放置返回或取消按钮。

我想为此制作一个取消按钮，但我无法制作取消按钮。我该如何解决这个问题？

当前代码

import Foundation
import UIKit

@available(iOS 11.0, *)
class DocumentBrowserViewController : UIDocumentBrowserViewController, UIDocumentBrowserViewControllerDelegate {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
         delegate = self
        
         browserUserInterfaceStyle = .dark
         view.tintColor = .white
    }
        
    func documentBrowser(_ controller: UIDocumentBrowserViewController, didRequestDocumentCreationWithHandler importHandler: @escaping (URL?, UIDocumentBrowserViewController.ImportMode) -> Void) {
        let newDocumentURL: URL? = nil
        
        // Set the URL for the new document here. Optionally, you can present a template chooser before calling the importHandler.
        // Make sure the importHandler is always called, even if the user cancels the creation request.
        if newDocumentURL != nil {
            importHandler(newDocumentURL, .move)
        } else {
            importHandler(nil, .none)
        }
    }
    
    func documentBrowser(_ controller: UIDocumentBrowserViewController, didPickDocumentURLs documentURLs: [URL]) {
        guard let sourceURL = documentURLs.first else { return }
        
        do{
           try presentDocument(at: sourceURL)
        } catch {
            Log.Debug("\(error)")
        }
    }
    
    func documentBrowser(_ controller: UIDocumentBrowserViewController, didImportDocumentAt sourceURL: URL, toDestinationURL destinationURL: URL) {
        // Present the Document View Controller for the new newly created document
        do{
            try presentDocument(at: sourceURL)
        } catch {
            Log.Debug("\(error)")
        }
    }
    
    func documentBrowser(_ controller: UIDocumentBrowserViewController, failedToImportDocumentAt documentURL: URL, error: Error?) {
        // Make sure to handle the failed import appropriately, e.g., by presenting an error message to the user.
    }
    
    func presentDocument(at documentURL: URL) throws {
        guard documentURL.startAccessingSecurityScopedResource() else {
            throw IXError.fileAcessFailed
        }
        
        let storyBoard = UIStoryboard(name: "Main", bundle: nil)
        let documentViewController = storyBoard.instantiateViewController(withIdentifier: "ViewController") as! ViewController
        
        documentViewController.document = Document(fileURL: documentURL)
    }
}

我想要的取消按钮图片

帮了我很多忙

提前致谢。

Answer 1

了解了 UIDocumentBrowserViewController 类，并成功添加了按钮。但是按钮的位置不是我想要的。

但这已经解决了我的基本问题，所以我将结束这个问题。

    override func viewDidLoad() {
        super.viewDidLoad()
        delegate = self
        allowsDocumentCreation = false
        allowsPickingMultipleItems = false
        browserUserInterfaceStyle = .dark
        view.tintColor = .white
        let cancelbutton = UIBarButtonItem(title: "Cancel", style: .plain, target: self, action: #selector(cancelButton(sender:)))
        additionalTrailingNavigationBarButtonItems = [cancelbutton]
    }

    @objc func cancelButton(sender: UIBarButtonItem) {
        dismiss(animated: true, completion: nil)
    }

Answer 2

我是否正确理解您想要在导航堆栈上推送一个 viewController (documentViewController) 并在 navigationBar 上有一个返回按钮来引导您返回主 viewController (DocumentBrowserViewController)？如果是这样，首先您需要将 documentViewController 推送到当前导航堆栈上。

首先是documentViewController出现了吗？

我看到的是您实例化了一个 documentViewController，将它的文档设置为 Document(...) 并结束。我不使用情节提要，但实例化是否呈现 viewController？

如果您提供更多详细信息，我将更新答案。但一般结论在您的 presentDocument(...) 中，您需要：

self.navigationController?.pushViewController(documentViewController, animated: true)