Almofire多张图片下载并保存到本地

如何解决Almofire多张图片下载并保存到本地

我有500多个图像链接，我想下​​载这些图像并在应用程序启动时本地存储在应用程序文档目录中。我正在使用Almofire下载，但出现了类似的错误 “ URLSession任务已取消”，并请求超时

func downloadAllImages(images:[String: String],retryCount: Int = 0,completion: @escaping((Bool)->Void)){
        var success: Bool = true
        var failedImages = [String: String]()
        for (localName,severPath) in images {
            self.dispatchGroup.enter()
            
            let destination: DownloadRequest.Destination = { _,_ in
                let documentsURL = FileManager.default.urls(for: .documentDirectory,in: .userDomainMask)[0]
                let fileURL = documentsURL.appendingPathComponent(localName)
                return (fileURL,[.removePreviousFile,.createIntermediateDirectories])
            }
           
            
            let path = severPath.replacingOccurrences(of: "\\",with: "/").addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed) ?? ""
        
            //AF.sessionConfiguration.httpShouldSetCookies = false
            AF.download(path,to: destination).response { response in
                switch response.result {
                case .success(_):
                    break
                case .failure(let error):
                    if response.response?.statusCode != 404 {
                        success = false
                        failedImages[localName] = path
                        print("Image Download Error = \(error.localizedDescription)")
                    }
                    break
                }
                debugPrint(response)
                self.dispatchGroup.leave()
            }
        }
        dispatchGroup.notify(queue: .main) {
            //retry If some Images failed to download
            if failedImages.isEmpty || retryCount >= self.maximumRetryCount {
                completion(success)
            }else {
                self.downloadAllImages(images: failedImages,retryCount: retryCount + 1) { (success) in
                    completion(success)
                }
            }
        }
    }

images词典包含 localName作为键 serverPath作为值

解决方法

AFImageDownloaders的活动下载有限制，我相信更改maximumActiveDownloads或您的API中的类似内容都可以解决此问题。新的下载只会取消以前的下载。但是最好分块下载它们。

例如，这个用于ImageDownloader

 public init(session: Session,downloadPrioritization: DownloadPrioritization = .fifo,maximumActiveDownloads: Int = 4,imageCache: ImageRequestCache? = AutoPurgingImageCache()) {
        precondition(!session.startRequestsImmediately,"Session must set `startRequestsImmediately` to `false`.")

        self.session = session
        self.downloadPrioritization = downloadPrioritization
        self.maximumActiveDownloads = maximumActiveDownloads
        self.imageCache = imageCache
    }

UPD： 限制不是自动对焦，而是URLSession。一个AF下载器使用一个URLSession。您必须通过自定义URLSessionConfigurations来处理更多活动下载HTTPMaximumConnectionsPerHost。并通过AF Session类