快速调用中缺少参数“ responder”的参数

Question

Ok so Im going a little crazy here trying to understand where is the problem with my code. Im trying to make separate classes communicate so I could handle UI elements during file download progression.

I went for a protocol solution that seems to fit my needs perfectly:

the protocol:

protocol DownloadResponder : class {
    func downloadFinished()
}

the download class: (for the sake of the question I only display the download_zip func and the didFinishDownloadingToURL delegate)

import UIKit
import Foundation

typealias CompleteHandlerBlock = () -> ()

class fileDownloader: NSObject, NSURLSessionDelegate, NSURLSessionDownloadDelegate {

    //responder
    var responder : DownloadResponder?

    init(responder : DownloadResponder) {
        self.responder = responder
    }

    var session: NSURLSession!
    var handlerQueue: [String : CompleteHandlerBlock]!

//    class var sharedInstance: fileDownloader {
//        struct Static {
//            static var instance : fileDownloader?
//            static var token : dispatch_once_t = 0
//        }
//        
//        dispatch_once(&Static.token) {
//            Static.instance = fileDownloader()
//            Static.instance!.handlerQueue = [String : CompleteHandlerBlock]()
//        }
//        
//        return Static.instance!
//    }

    func download_zip(sURL: String, destination:String, name:String, fileis:Int) {

        var session:NSURLSessionTask!
        var sessionConfiguration:NSURLSessionConfiguration = NSURLSessionConfiguration.backgroundSessionConfigurationWithIdentifier("com.visi")
        sessionConfiguration.HTTPMaximumConnectionsPerHost = 5

        self.session = NSURLSession(configuration: sessionConfiguration, delegate: self, delegateQueue: nil)
        var url = NSURLRequest(URL: NSURL(string: sURL)!)
        var downloadTask:NSURLSessionDownloadTask = self.session.downloadTaskWithRequest(url)

        downloadTask.resume()
    }

    func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didFinishDownloadingToURL location: NSURL) {
        println("session \(session) has finished the download task \(downloadTask) of URL \(location).")

        responder?.downloadFinished()
    }

the downloadFinished func in my FileInfo ViewController :

func downloadFinished() {
        downloadLbl.text = "Downloaded"
        println("DOWNLOAD OVER")
    }

and finally, the function in my FileInfo ViewController :

func downloadFile(sender:UIButton!)
    {
     // some code...   

     fileDownloader().download_zip(datastring, destination: path, name: naming, fileis: self.fileId)
    }

this func call fileDownloader().download_zip(datastring, destination: path, name: naming, fileis: self.fileId) in my view controller triggers an error I didn't have before I add the protocol. It says: Missing argument for parameter 'responder' in call . I can't think of any solution so if someone knows what it is please help!

Answer 1

In your init method of fileDownloader you are expecting a parameter responder: DownloadResponder which you are not providing when you are initializing the fileDownloader in the downloadFile method.

So instead of:

fileDownloader().download_zip(...

Do:

fileDownloader(DownloadResponderImplementation()).download_zip(...

This assumes you to also Implement the DownloadResponder protocol as for example:

class DownloadResponderImplementation: DownloadResponder {
   func downloadFinished() {
      //Do something here
   }
}