Build robust and resumable file transfers

4:53 - Pausing and resuming a URLSessionDownloadTask

let downloadTask = session.downloadTask(with: request)
downloadTask.resume()

5:21 - Pausing and resuming a URLSessionDownloadTask

let downloadTask = session.downloadTask(with: request)
downloadTask.resume()

guard let resumeData = await downloadTask.cancelByProducingResumeData() else {
    // Download cannot be resumed
    return
}

6:11 - Pausing and resuming a URLSessionDownloadTask

let downloadTask = session.downloadTask(with: request)
downloadTask.resume()

guard let resumeData = await downloadTask.cancelByProducingResumeData() else {
    // Download cannot be resumed
    return
}

let newDownloadTask = session.downloadTask(withResumeData: resumeData)
newDownloadTask.resume()

6:34 - Retrieving resume data on error

do {
    let (url, response) = try await session.download(for: request)
} catch let error as URLError {
    guard let resumeData = error.downloadTaskResumeData else {
        // Download cannot be resumed
        return
    }
}

8:29 - Pausing and resuming a URLSessionUploadTask

let uploadTask = session.uploadTask(with: request, fromFile: fileURL)
uploadTask.resume()

8:37 - Pausing and resuming a URLSessionUploadTask

let uploadTask = session.uploadTask(with: request, fromFile: fileURL)
uploadTask.resume()

guard let resumeData = await uploadTask.cancelByProducingResumeData() else {
    // Upload cannot be resumed
    return
}

8:57 - Pausing and resuming a URLSessionUploadTask

let uploadTask = session.uploadTask(with: request, fromFile: fileURL)
uploadTask.resume()

guard let resumeData = await uploadTask.cancelByProducingResumeData() else {
    // Upload cannot be resumed
    return
}

let newUploadTask = session.uploadTask(withResumeData: resumeData)
newUploadTask.resume()

9:22 - Retrieving resume data on error

do {
    let (data, response) = try await session.upload(for: request, fromFile: fileURL)
} catch let error as URLError {
    guard let resumeData = error.uploadTaskResumeData else {
        // Upload cannot be resumed
        return
    }
}

13:15 - Before resumable uploads in Swift NIO

NIOTSListenerBootstrap(group: NIOTSEventLoopGroup())
    .childChannelInitializer { channel in
        channel.configureHTTP2Pipeline(mode: .server) { channel in
            channel.pipeline.addHandlers([
                HTTP2FramePayloadToHTTPServerCodec(),
                ExampleChannelHandler()
            ])
        }.map { _ in () }
    }
    .tlsOptions(tlsOptions)

14:06 - Add resumable uploads in Swift NIO

import NIOResumableUpload

let uploadContext = HTTPResumableUploadContext(origin: "https://example.com")

NIOTSListenerBootstrap(group: NIOTSEventLoopGroup())
    .childChannelInitializer { channel in
        channel.configureHTTP2Pipeline(mode: .server) { channel in
            channel.pipeline.addHandlers([
                HTTP2FramePayloadToHTTPServerCodec(),
                HTTPResumableUploadHandler(context: uploadContext, handlers: [
                    ExampleChannelHandler()
                ])
            ])
        }.map { _ in () }
    }
    .tlsOptions(tlsOptions)

15:48 - Informational responses in URLSession

protocol URLSessionTaskDelegate : URLSessionDelegate {
    optional func urlSession(_ session: URLSession, task: URLSessionTask,
                             didReceiveInformationalResponse response: HTTPURLResponse)
}

18:19 - Using background URLSession

// Configuring your background session
let configuration = URLSessionConfiguration.background(withIdentifier: "com.example.app")
configuration.isDiscretionary = true
configuration.allowsConstrainedNetworkAccess = false
let session = URLSession(configuration: configuration, delegate: self, delegateQueue: nil)

// Configuring your background task
let backgroundTask = session.uploadTask(with: url, fromFile: fileURL)
backgroundTask.earliestBeginDate = .now.addingTimeInterval(60 * 60)
backgroundTask.countOfBytesClientExpectsToSend = 500 * 1024
backgroundTask.countOfBytesClientExpectsToReceive = 200