从 USB-C 驱动器和 iPad iOS13 读取文件和内容

Posted 2023-02-23

【中文标题】从 USB-C 驱动器和 iPad iOS13 读取文件和内容

【英文标题】：Read files and contents from USB-C drive and iPad iOS13

【发布时间】：2019-10-08 13:26:44

【问题描述】：

我创建了一个 UIDocumentPickerViewController 并在 USB 驱动器上选择了我的文件夹，在使用枚举器列出文件后，我如何读取内容？

你能读取文件的内容吗？

这是我的示例代码：

@IBAction func openFiles(_ sender: Any) 

        // Using the Document Picker to Pick a Folder
        let documentPicker = UIDocumentPickerViewController(documentTypes: [kUTTypeFolder as String], in: .open)
        documentPicker.delegate = self
        documentPicker.shouldShowFileExtensions = true
        present(documentPicker, animated: true, completion: nil)
    

@IBAction func readFiles()  
        // Reading the Content of a Picked Folder  
        let shouldStopAccessing = pickedFolderURL.startAccessingSecurityScopedResource()  
        defer   
            if shouldStopAccessing   
                pickedFolderURL.stopAccessingSecurityScopedResource()  
              
          
        var coordinatedError:NSError?  
        NSFileCoordinator().coordinate(readingItemAt: pickedFolderURL, error: &coordinatedError)  (folderURL) in  
            let keys : [URLResourceKey] = [.nameKey, .isDirectoryKey]  
            let fileList = FileManager.default.enumerator(at: pickedFolderURL, includingPropertiesForKeys: keys)!  
            logString = ""  
            for case let file as URL in fileList   

                let newFile = file.path.replacingOccurrences(of: pickedFolderURL.path, with: "")  
                if(newFile.hasPrefix("/.") == false) //exclude hidden  

                    print(file)  
                    logString += "\n\(file)"  
                    if (file.pathExtension == "mp4")  
                        self.pickedVideoURL = file  
                      
                    if (file.pathExtension == "txt")  
                        self.pickedTextURL = file  
                      
                  
              
            self.logTextView.text = logString  
          
      

现在我想读取 txt/mp4 文件的内容...如何？ 使用 quicklook 或 AVPlayerViewController 我得到阅读错误...

你有示例项目吗？

【问题讨论】：

我在这里有几乎完全相同的问题——***.com/questions/60498625/…

你必须使用securityScope和coordinator的组合。

【参考方案1】：

解决方案是结合使用securityScope和文件NSFileCoordinator

@IBAction func readFiles()
        // Reading the Content of a Picked Folder
 // pickedFolderURL must be a fileURL
        let shouldStopAccessing = pickedFolderURL.startAccessingSecurityScopedResource()
        defer 
            if shouldStopAccessing 
                pickedFolderURL.stopAccessingSecurityScopedResource()
            
        
        var coordinatedError:NSError?
        NSFileCoordinator().coordinate(readingItemAt: pickedFolderURL, error: &coordinatedError)  (folderURL) in
            let keys : [URLResourceKey] = [.nameKey, .isDirectoryKey]
            let fileList = FileManager.default.enumerator(at: pickedFolderURL, includingPropertiesForKeys: keys)!
            for case let file as URL in fileList 

                guard pickedFolderURL.startAccessingSecurityScopedResource() else 
                    fatalError("Handle the failure here.")
                    return;
                        
                // Make sure you release the security-scoped resource when you are done.
                defer  pickedFolderURL.stopAccessingSecurityScopedResource() 

                let newFile = file.path.replacingOccurrences(of: pickedFolderURL.path, with: "")
                if(newFile.hasPrefix("/.") == false) //exclude hidden
                    print(file)
                
            
            self.logTextView.text = logString
        
    

【讨论】：

您的意思是再次guard pickedFolderURL 还是guard file？无论哪种方式 - 我尝试对文件进行安全范围限制，并且总是在 fatalError 部分结束

确定文件夹的范围将使您能够递归地访问整个子文件夹...我认为错误在别处

@Kal 无论如何我再次尝试了这段代码，它在没有权限错误的情况下工作。