Swift upload multiple files parallel into AWS S3 and show progress view status in tableview cell

Question

I am new for AWS, I have done some file uploading into AWS S3 with TransferUtility file transformation. Here my scenario steps

1. Picking the files from iCloud

public func documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentAt url: URL) {

        let fileurl: URL = url as URL
        let filename = url.lastPathComponent
        let file-extension = url.pathExtension
        let filedata = url.dataRepresentation

        // Call upload function
        upload(file: fileurl, keyname: filename, exten: file-extension)

        // Append names into array
        items.append(item(title: filename, size: string))
        self.tableView_util.reloadData()

2. Upload that file into AWS S3 with transfer-utility

private func upload(file url: URL, keyname : String, exten: String) {
 transferUtility.uploadfile(file ur,
        bucket: "YourBucket",
        key: "YourFileName",
        contentType: "text/plain",
        expression: expression,
        completionHandler: completionHandler).continueWith {
           (task) -> AnyObject! in
               if let error = task.error {
                  print("Error: \(error.localizedDescription)")
               }

               if let _ = task.result {
                  // Do something with uploadTask.
               }
               return nil;
       }

3. While upload need to show each file uploading status into tableview cell

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        let cell = tableView.dequeueReusableCell(withIdentifier: "cellutil", for: indexPath) as! UtilityTableViewCell
        let item = items[indexPath.row]
}

My Issue: The tableview I can able to show uploading items but first uploading stopped when I upload next one. I need to achieve parallel upload multiple files and show on cell status.

Answer 1

To do that you create a Operation queue, and each upload file write network request inside of operation and add these operations to queue.

Here I am giving to hint to do this.

Create a model class that has properties like

struct UploadRecordData { 
    let fileName:String
    let unique_id:String
    let progress:double
    //...etc
}

and then sub-class of operation like this

    struct UploadRecordOperation:Operation{
        let uploadRecordData:UploadRecordData
        //etc..

        //update progess inside of operation class
        func updateProgress(progress:Double){
            uploadRecordData.progress = progress
            //edited answer
            let myDict = [ "progress": progress, "unique_id":unique_id]
          NSNotificationCenter.defaultCenter().postNotificationName("refreshProgressBar", object:myDict);
        }
    }

Now here is the part of table view controller

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier(textCellIdentifier, forIndexPath: indexPath)

    let row = indexPath.row
    let uploadRecordData = uploadfilesRecords[row]
    //edited answer  
    cell.progressView.uniqud_id = uploadRecord.unique_id
    cell.progressView.progress = uploadRecord.progress
    return cell
}

Here is way to refresh cell while updating refresh upload files progress.

Sub-class of your progress view like this

struct ProgressView:YourProgressView{
            var unique_id:int

            //Now add notification observer to your progress view
            NotificationCenter.default.addObserver(self, selector: #selector(refreshProgressView), name: "refreshProgressBar", object: nil)


            func refreshProgressView(notification: NSNotification){
                let dict = notification.object as! NSDictionary
                let progress = dict["progress"]
                let u_id = dict["unique_id"]

                if u_id == self.unique_id {
                    self.progress = progress
                }
            }

Please see above updated code in Operation subclass and table view delegate method.