Calling parent method from a class

Question

I am creating a new Downloader object (simply to download PDF files) and I need to call a method in my ViewController which show the message that the file is successfully downloaded. I am using the answer by Ahmet Akkök on this question and when I try to use yourOwnObject.showDownloadCompleted() it can't find the method.

ViewController:

override func viewDidLoad(){
    super.viewDidLoad();
    let pdfURL = "exampleToPFD.com/mypdf.pdf";
    let url = NSURL(string: pdfURL);
    let d = Downloader(yourOwnObject: self);
    d.download(url!);

}

func showDownloadComplete(){
    print("done");
}

Downloader:

import Foundation

class Downloader : NSObject, NSURLSessionDownloadDelegate {
    var url : NSURL?

    // will be used to do whatever is needed once download is complete
    var yourOwnObject : NSObject?
    var downloaded = false;
    var documentDestination = "";

    init(yourOwnObject : NSObject){
        self.yourOwnObject = yourOwnObject
    }


    // is called once the download is complete
    func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didFinishDownloadingToURL location: NSURL) {
        //copy downloaded data to your documents directory with same names as source file
        let documentsUrl =  NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask).first
        let destinationUrl = documentsUrl!.URLByAppendingPathComponent(url!.lastPathComponent!)
        let dataFromURL = NSData(contentsOfURL: location)
        dataFromURL!.writeToURL(destinationUrl, atomically: true)
        
        // now it is time to do what is needed to be done after the download
        
        print("download done...");
        // call to the parent method here
        
        documentDestination = destinationUrl.absoluteString;
        print("DestURL" + (destinationUrl.absoluteString));
    }

    // method to be called to download
    func download(url: NSURL) {
        self.url = url
        
        // download identifier can be customized. I used the "ulr.absoluteString"
        let sessionConfig = NSURLSessionConfiguration.backgroundSessionConfigurationWithIdentifier(url.absoluteString)
        let session = NSURLSession(configuration: sessionConfig, delegate: self, delegateQueue: nil)
        let task = session.downloadTaskWithURL(url);
        
        task.resume();
    }
}

Answer 1

You can use delegate to achieve that. You can try out following

Downloader.swift

import Foundation

protocol DownloadDelegate {
    func downloadCompleted()
}

class Downloader : NSObject, NSURLSessionDownloadDelegate{
var url : NSURL?
var downloadDelegate : DownloadDelegate!
// will be used to do whatever is needed once download is complete
var downloaded = false;
var documentDestination = "";

//is called once the download is complete
func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didFinishDownloadingToURL location: NSURL){
    //copy downloaded data to your documents directory with same names as source file
    let documentsUrl =  NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask).first
    let destinationUrl = documentsUrl!.URLByAppendingPathComponent(url!.lastPathComponent!)
    let dataFromURL = NSData(contentsOfURL: location)
    dataFromURL!.writeToURL(destinationUrl, atomically: true)

    //now it is time to do what is needed to be done after the download

    print("download done...");
    downloadDelegate. downloadCompleted()

    documentDestination = destinationUrl.absoluteString;
    print("DestURL" + (destinationUrl.absoluteString));
}

//this is to track progress
func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64){
    print((String)(totalBytesWritten)+"/"+(String)(totalBytesExpectedToWrite));

}

// if there is an error during download this will be called
func URLSession(session: NSURLSession, task: NSURLSessionTask, didCompleteWithError error: NSError?){

    if(error != nil){

        //handle the error
        print("Download completed with error: \(error!.localizedDescription)");

    }

}


//method to be called to download
func download(url: NSURL){

    self.url = url

    //download identifier can be customized. I used the "ulr.absoluteString"
    let sessionConfig = NSURLSessionConfiguration.backgroundSessionConfigurationWithIdentifier(url.absoluteString)
    let session = NSURLSession(configuration: sessionConfig, delegate: self, delegateQueue: nil)
    let task = session.downloadTaskWithURL(url);

    task.resume();
}
}

ViewController :

class ViewController: UIViewController,DownloadDelegate{
    override func viewDidLoad(){

        super.viewDidLoad();
        // Do any additional setup after loading the view, typically from a nib.
        let pdfURL = "exampleToPFD.com/mypdf.pdf";

        let url = NSURL(string: pdfURL);

        let d = Downloader();
        d.downloadDelegate = self
        d.download(url!);


        showToast("Download Started...");

    }

    func downloadCompleted() {
       //download completed
    }
}