Issue with updating clicked table view cell - ios

Question

I have an issue that has been vexing me for a while and I feel like I am so close. Here is the situation. I have a tableview that holds different calculus videos and I would like to give my students the ability to download the videos for playing offline. That part works fine. The problem I am having is that when the user clicks on the download button, the download button should hide and show an activity indicator as well as a progress bar (all of which are in a custom cell). I have two problems:
1) The download button does not automatically hide and show the activity view unless I scroll away from it and come back to it.
2) If I do scroll down all of a sudden random cells will not have the download button anymore.
This must be due to the fact that cells are being reused but I thought I was doing things properly although obviously there is a mistake. I will post the relevant code snippets below:
cellForRowAtIndexPath Code:
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("VideoCell", forIndexPath: indexPath) as! TableViewCell
let currentVideo = videos[indexPath.section][indexPath.row]
cell.downloadButton.addTarget(self, action: "downloadButtonPressed:", forControlEvents: .TouchUpInside)
cell.video = currentVideo
return cell
}
Custom Table View Cell Code:
class TableViewCell: UITableViewCell {
#IBOutlet weak var videoTitleLabel: UILabel!
#IBOutlet weak var progressView: UIProgressView!
#IBOutlet weak var customAccessoryView: UIView!
#IBOutlet weak var downloadButton: UIButton!
#IBOutlet weak var activityIndicator: UIActivityIndicatorView!
let userDefaults = NSUserDefaults.standardUserDefaults()
var video: Video? {
didSet {
updateUI()
}
}
private func updateUI() {
guard let video = video else {
print("video should not be nil")
return
}
videoTitleLabel.text = video.title
if video.downloadStatus.isDownloading {
progressView.hidden = false
progressView.progress = video.downloadStatus.downloadProgress
downloadButton.hidden = true
activityIndicator.hidden = false
activityIndicator.startAnimating()
} else {
progressView.hidden = true
activityIndicator.stopAnimating()
}
if video.downloadStatus.isSaved {
activityIndicator.stopAnimating()
progressView.hidden = true
downloadButton.hidden = true
}
}
Download request
func downloadButtonPressed(sender: UIButton) {
let buttonPosition = sender.convertPoint(CGPointZero, toView: self.tableView)
guard let indexPath = self.tableView.indexPathForRowAtPoint(buttonPosition) else {
print("Error getting index path from button press")
return
}
let section = indexPath.section
let row = indexPath.row
print("Button pressed at section \(section) and row \(row)")//correct row and section
//Code to save Video to Documents directory goes here
let currentVideo = videos[section][row]
guard !currentVideo.downloadStatus.isSaved else {
print("Video is already saved")
return
}
guard let url = currentVideo.url else {
print("Video not found...url is invalid")
return
}
let destination = Alamofire.Request.suggestedDownloadDestination(directory: .DocumentDirectory, domain: .UserDomainMask)
Alamofire.download(.GET, url, destination: destination)
.progress { bytesRead, totalBytesRead, totalBytesExpectedToRead in
let progress = Float(totalBytesRead) / Float(totalBytesExpectedToRead)
currentVideo.downloadStatus.isDownloading = true
currentVideo.downloadStatus.downloadProgress = progress
}.response { request,response,data, error in
if let error = error {
print("Failed with error: \(error)")
} else {
print("Downloaded file successfully")
currentVideo.downloadStatus.isDownloading = false
currentVideo.downloadStatus.isSaved = true
self.saveDownloadStatusInDefaultsForVideo(currentVideo, isSaved: true)
}
print("Files currently in the documents directory:")
self.printDocumentsDirectoryContents() //file is there
}
}

Answer 1

In your class TableViewCell you're setting the property hidden of downloadButton to true under certain circumstances.
If you want the button to be visible by default set the property explicitly to false when reusing the cell