`URLSessionDelegate` methods are not called

Question

Please, note that I've checked previous answers and I am not using callbacks in the code. In this case the delegate methods should be called

Environment iOS 14.4.2

URL is valid. File is downloaded. Just the delegate not get called.

The example code is below:

final class Downloader: NSObject, URLSessionDelegate {

    private lazy var urlSession = URLSession(
        configuration: .default,
        delegate: self,
        delegateQueue: .main
    )
    private var downloadTask: URLSessionDownloadTask?

    func beginDownload(url: URL) {
        downloadTask = urlSession.downloadTask(with: url)
        downloadTask!.resume()
    }

    func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
        // NEVER CALLED
    }
}

how is the `Downloader` class created? Is it retained? perhaps it gets deallocated right after being created — Adam, May 24 '21 at 09:38
@Sh_Khan, Downloader is created and retained in another place. — fewlinesofcode, May 24 '21 at 09:42
Are you sure the download task actually finishes at all? Also, the method you're implementing is part of `URLSessionDownloadDelegate`, not `URLSessionDelegate`, so you should declare conformance to `URLSessionDownloadDelegate` as well. — Dávid Pásztor, May 24 '21 at 09:49
@DávidPásztor, you're right. The problem was I had conformance to `URLSessionDataDelegate` instead of `URLSessionDownloadDelegate` — fewlinesofcode, May 24 '21 at 09:52
@DávidPásztor, please, add it as an answer so I can accept it. — fewlinesofcode, May 24 '21 at 09:53

score 2 · Accepted Answer · answered May 24 '21 at 10:01

The func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) method you're implementing is part of URLSessionDownloadDelegate, not URLSessionDelegate, so you should declare conformance to URLSessionDownloadDelegate as well in order for the delegate call to occur.

`URLSessionDelegate` methods are not called

1 Answers1