Almofire multiple images Download and save them locally - ios

Question

I have more than 500 image links I want to download those images and store locally in app document directory when app starts. I am using Almofire for download but I am getting error like
"URLSession task was cancelled" and Request timeOut
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 dictionary contains
localName as key
serverPath as value

Answer 1

AFImageDownloaders have limit of active downloads, and I believe changing maximumActiveDownloads or something similar in your API will fix that. The new downloads just cancel the previous ones. But it's better to download them in chunks.
For example this one is for 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:
The limit is not on AF, but URLSession's. And one AF downloader uses one URLSession. You have to pass custom URLSessionConfigurations to handle more active downloads HTTPMaximumConnectionsPerHost. And pass it AF Session class