chriswebb09

extension ExampleViewController: DownloadDelegate {
    
    func downloadProgressUpdated(for progress: Float) {
        DispatchQueue.main.async {
            self.progressView.progress += progress
            self.downloadProgressLabel.text =  String(format: "%.1f%%", progress * 100)
        }
    }
}

chriswebb09

final class Download {

    weak var delegate: DownloadDelegate?
    
    // Other properties 
    
    var progress: Float = 0.0 {
        didSet {
            updateProgress()
        }

chriswebb09

protocol DownloadDelegate: class {
    func downloadProgressUpdate(for progress: Float)
}

chriswebb09

protocol DownloadDelegate: class {
    // Delegate method
}

chriswebb09

final class Download {
    
    weak var delegate: DownloadDelegate?
    var url: String?
    var downloadTask: URLSessionDownloadTask?
    
    var progress: Float = 0.0 {
        didSet {
            updateProgress()
            if progress == 1 {

chriswebb09

extension iTunesAPIClient: URLSessionDelegate {
    
    internal func urlSessionDidFinishEvents(forBackgroundURLSession session: URLSession) {
        if let appDelegate = UIApplication.shared.delegate as? AppDelegate,
            let completionHandler = appDelegate.backgroundSessionCompletionHandler {
            appDelegate.backgroundSessionCompletionHandler = nil
            DispatchQueue.main.async {
                completionHandler()
            }
        }

chriswebb09

class AppDelegate: UIResponder, UIApplicationDelegate {
    var backgroundSessionCompletionHandler: (() -> Void)?
    
    // AppDelegate functionality. 
 }

chriswebb09

func application(_ application: UIApplication, handleEventsForBackgroundURLSession identifier: String, completionHandler: @escaping () -> Void) {
    // Background completion called here.
}

chriswebb09

extension iTunesAPIClient: URLSessionDelegate {
    internal func urlSessionDidFinishEvents(forBackgroundURLSession session: URLSession) {
         // Calls background session completion in AppDelegate
    }
    
    internal func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64,totalBytesExpectedToWrite: Int64) {
        // Gives you the URLSessionDownloadTask that is being executed
        // along with the total file length - totalBytesExpectedToWrite
        // and the current amount of data that has received up to this point - totalBytesWritten
   }

chriswebb09

final class iTunesAPIClient: NSObject {
    // Network stuff
}