How can I create protocol delegate to observe Alamofire progress and to use in ViewController swift

Question

How can I create protocol (delegate function) in Alamofire download function which will observe progress.fraction And then I can use it in any viewController tableView?

My Alamofire function is in main common class and I have to retrieve progress values of file downloads.

Alamofire Download Function

@objc public func downloadFile(url:String, filetype: String, callback:@escaping (_ success:Bool, _ result:Any?)->(Bool)) -> Void {
        var destination = DownloadRequest.suggestedDownloadDestination(for: .documentDirectory)
        if filetype.elementsEqual(".pdf"){
            destination = { _, _ in
                let documentsURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
                let downloadFileName = url.filName()
                let fileURL = documentsURL.appendingPathComponent("\(downloadFileName).pdf")
                return (fileURL, [.removePreviousFile, .createIntermediateDirectories])
            }
        } 

        Alamofire.download(
            url,
            method: .get,
            parameters: nil,
            encoding: JSONEncoding.default,
            headers: nil,
            to: destination).downloadProgress(closure: { (progress) in
                //progress closure
                print(progress.fractionCompleted)

            }).response(completionHandler: { (DefaultDownloadResponse) in
                callback(DefaultDownloadResponse.response?.statusCode == 200, DefaultDownloadResponse.destinationURL?.absoluteString.replacingOccurrences(of: "file://", with: ""))
                print(DefaultDownloadResponse)
            })
    }

andromedainiative · Answer 1 · 2020-01-16T09:40:59.007

Something like this:

protocol MyWebServiceProtocol: class {
   func progress(_ fractionCompleted: Int)
   func downloadDidSucceed(data: Data)
   func downloadDidFail(error: Error)
}

class MyViewController: UIViewController {

    let webService: MyWebService

    init(webService: MyWebService = MyWebService()) {
        self.webService = webService
        super.init(nibName: nil, bundle: nil)
        self.webService.delegate = self
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }


}

extension MyViewController: MyWebServiceProtocol {
    func progress(_ fractionCompleted: Int) {
       print(fractionCompleted) // do something with progress
    }

    func downloadDidSucceed(data: Data) {
         // Do something here
    }

    func downloadDidFail(error: Error) {
        // handle error
    }
}

class MyWebService {

    weak var delegate: MyWebServiceProtocol?

    @objc public func downloadFile(url:String, filetype: String, callback:@escaping (_ success:Bool, _ result:Any?)->(Bool)) -> Void {
        var destination = DownloadRequest.suggestedDownloadDestination(for: .documentDirectory)
        if filetype.elementsEqual(".pdf"){
            destination = { _, _ in
                let documentsURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
                let downloadFileName = url.filName()
                let fileURL = documentsURL.appendingPathComponent("\(downloadFileName).pdf")

                return (fileURL, [.removePreviousFile, .createIntermediateDirectories])
        }
    } 

    Alamofire.download(
        url,
        method: .get,
        parameters: nil,
        encoding: JSONEncoding.default,
        headers: nil,
        to: destination).downloadProgress(closure: { [weak self] (progress) in
            //progress closure
            self?.delegate?.progress(progress.fractionCompleted)
            print(progress.fractionCompleted)

        }).response(completionHandler: { [weak self] (DefaultDownloadResponse) in
            callback(DefaultDownloadResponse.response?.statusCode == 200, DefaultDownloadResponse.destinationURL?.absoluteString.replacingOccurrences(of: "file://", with: ""))
            self?.delegate?.downloadDidSucceed()
            print(DefaultDownloadResponse)
        })
}

I have tried to implement that but getting an error. Can you please check? https://stackoverflow.com/questions/59764565/how-to-set-protocol-function-not-properly-invoke-in-dataprovider-class-alamofire — , Jan 16 '20 at 07:44
Now on `fatalError` it gives me error `Fatal error: init(coder:) has not been implemented: file /Users/macuser/Documents/XCodeWork/ABC/ABC/ViewControllers/DownloadViewController.swift ` — , Jan 16 '20 at 08:33
If you are creating this view controller without a link to a nib it will work. If you have a nib file connected this init will not work. — andromedainiative, Jan 16 '20 at 09:40
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/206051/discussion-between-andromedainiative-and-newbie-mobile). — andromedainiative, Jan 16 '20 at 09:41

How can I create protocol delegate to observe Alamofire progress and to use in ViewController swift

1 Answers1