解压缩文件之前的额外检查

Question

我下载了一个文件并想要解压缩它。我的代码工作正常。但有一个问题。我接到

didFinishDownloadingTo

的电话后立即开始解压文件。这是正确的行为吗？在开始解压之前我需要做任何额外的检查吗？例如，该文件是否存在于目录中？或者已经准备好解压了吗？是否有可能下载成功后解压前出现无法解压文件的问题？

视图控制器：

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    
    let url = URL(string: "0.zip")!
    let downloadManager = DownloadManager()
    downloadManager.identifier = indexPath.row+1
    downloadManager.collectionId = 0
    downloadManager.folderPath = "\(indexPath.row+1)"
    let downloadTaskLocal = downloadManager.activate().downloadTask(with: url)
    downloadTaskLocal.resume()
                
    downloadManager.onSuccess = { [weak self] row in
        guard let self = self else { return }
        DispatchQueue.main.async {
            self.items[row - 1].state = .completed
            self.reloadItem(indexPath: .init(row: row - 1, section: 0))
            
            if self.items[row - 1].state == .completed {
                var zip = []
                zip.append(row - 1)
            }
            
            if fileManager.fileExists(atPath: destination.path){
                let sourceURL = URL(fileURLWithPath: "\(destination.path)/1.zip")
                let destinationURL = URL(fileURLWithPath: destination.path)
                
                let unzipProgress = Progress()
                let observation = unzipProgress.observe(\.fractionCompleted) { progress, _ in
                    print("Extraction progress: ", progress.fractionCompleted)
                    if progress.fractionCompleted == 1.0 {
                        self.items[row - 1].state = .unzipped
                        self.reloadItem(indexPath: .init(row: row - 1, section: 0))
                    }
                }
                
                do { try fileManager.unzipItem(at: sourceURL, to: destinationURL, progress: unzipProgress) }
                catch { print("error") }
                
                observation.invalidate()
                
            } else { print("error") }
            
        }
    }
}

下载管理器：

func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL){
    
    let stringNumb = (session.accessibilityHint ?? "hit")
    let someNumb = Int(stringNumb as String)
    
    let string1 = (session.sessionDescription ?? "hit")
    let some1 = Int(string1 as String)
    
    if let idx = downloadQueue[someNumb!]?.index(of: some1!) {
        downloadQueue[someNumb!]?.remove(at: idx)
        print("remove:\(downloadQueue)")
    }
    
    let fileName = downloadTask.originalRequest?.url?.lastPathComponent
    let path = NSSearchPathForDirectoriesInDomains(FileManager.SearchPathDirectory.documentDirectory, FileManager.SearchPathDomainMask.userDomainMask, true)
    let documentDirectoryPath:String = path[0]
    let fileManager = FileManager()
    var destinationURLForFile = URL(fileURLWithPath: documentDirectoryPath.appending("/\(folderPath)"))
    
    do {
        try fileManager.createDirectory(at: destinationURLForFile, withIntermediateDirectories: true, attributes: nil)
        destinationURLForFile.appendPathComponent(String(describing: fileName!))
        try fileManager.moveItem(at: location, to: destinationURLForFile)
        onSuccess?(identifier)
    } catch (let error) {
        print(error)
    }
}

Answer 1

根据@HangarRash 的建议，我添加了以下更改：

DispatchQueue.global().async {
    do { try fileManager.unzipItem(at: sourceURL, to: destinationURL, progress: unzipProgress) }
    catch {  print("error") }
}

完整代码：

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    
    let url = URL(string: "1.zip")!
    let downloadManager = DownloadManager()
    downloadManager.identifier = indexPath.row+1
    downloadManager.collectionId = 0
    downloadManager.folderPath = "\(indexPath.row+1)"
    let downloadTaskLocal = downloadManager.activate().downloadTask(with: url)
    downloadTaskLocal.resume()
    
    downloadManager.onSuccess = { [weak self] row in
        guard let self = self else { return }
        DispatchQueue.main.async {
            self.items[row - 1].state = .completed
            self.reloadItem(indexPath: .init(row: row - 1, section: 0))
            
            if fileManager.fileExists(atPath: destination.path){
                let sourceURL = URL(fileURLWithPath: "\(destination.path)/1.zip")
                let destinationURL = URL(fileURLWithPath: destination.path)
                let unzipProgress = Progress()
                let observation = unzipProgress.observe(\.fractionCompleted) { progress, _ in
                    print("Extraction progress: ", progress.fractionCompleted)
                    if progress.fractionCompleted == 1.0 {
                        self.items[row - 1].state = .unzipped
                        self.reloadItem(indexPath: .init(row: row - 1, section: 0))
                    }
                }
                DispatchQueue.global().async {
                    do { try fileManager.unzipItem(at: sourceURL, to: destinationURL, progress: unzipProgress) }
                    catch {  print("error") }
                }
                observation.invalidate()
            } else { print("error") }
        }
    }
    
}