Issue with requesting the video thumbnail using MPMoviePlayer

Question

I am trying to parse the JSON data which has video urls and the title. After parsing the data I am showing the video thumbnail in a UITableviewCell. The problem is that when the data is parsed and when its time to request for the thumbnail the NSNotification selector method is never been called. Here is my code:

override func viewDidLoad() { 
super.viewDidLoad() 
getJson_results() 
}

override func viewWillDisappear(animated: Bool) {
NSNotificationCenter.defaultCenter().removeObserver(self)
}

func videoThumbnailIsAvailable(notification: NSNotification) {
    println("Flag1") //the control never reaches here
    var thumbnail = notification.userInfo?[MPMoviePlayerThumbnailImageKey] as UIImage
    self.temp_image = thumbnail
}


func videodurationIsAvailable(notification: NSNotification) {
    var val = moviePlayer?.duration
    self.temp_duration = val!
}

override func tableView(tableView: UITableView, numberOfRowsInSection section:    Int) -> Int { 
    return length_array; 
}

override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as WPR_Main
    cell.imgView?.image =           get_Media_thumbnail(NSURL(string:self.url[indexPath.row])!)
    cell.titleLabel?.text = self.titles[indexPath.row]
    return cell
    }


func get_Media_thumbnail(url: NSURL) -> UIImage {
    moviePlayer? = MPMoviePlayerController(contentURL: url)
    NSNotificationCenter.defaultCenter().addObserver(self,
    selector: "videoThumbnailIsAvailable:",
    name: MPMoviePlayerThumbnailImageRequestDidFinishNotification,
    object: nil)
    moviePlayer?.requestThumbnailImagesAtTimes([1.0], timeOption:.NearestKeyFrame )
   return self.temp_image
}

score 0 · Accepted Answer · answered Feb 22 '15 at 21:47

The best way to achieve this is to use AVAssetImageGenerator instead of using requestThumbnailImagesAtTimes. AVAsset also allow to download the images asynchronously which is quite faster and applicable to the requirement. Here is the code:

var urlAsset = AVURLAsset(URL: NSURL(string:self.url[indexPath.row])!, options: nil)
        if(urlAsset.tracksWithMediaType(AVMediaTypeVideo).count > 0){
            var imageGenerator = AVAssetImageGenerator(asset: urlAsset)
            imageGenerator.appliesPreferredTrackTransform=true
            let durationSeconds = CMTimeGetSeconds(urlAsset.duration)
            let midPoint = CMTimeMakeWithSeconds(durationSeconds/2, 1)
            var error:NSError? = nil
            var actualTime = CMTimeMake(0, 0)
            imageGenerator.generateCGImagesAsynchronouslyForTimes( [ NSValue(CMTime:midPoint) ], completionHandler: {
                (requestTime, thumbnail, actualTime, result, error) -> Void in

                if result == AVAssetImageGeneratorResult.Succeeded {

                    dispatch_async(dispatch_get_main_queue()) {
                        var thumbnailImage = UIImage(CGImage: thumbnail)
                        cell.imgView?.image =  thumbnailImage
                    }//dispatch
                }//if
                else {
                    var thumbnailImage = UIImage(named: "video-backup.png")
                    cell.imageView?.contentMode = .ScaleAspectFit
                    cell.imgView?.image =  thumbnailImage
                }
            })

I'm trying to use the generateCGImagesAsynchronouslyForTimes method but it takes forever and freezes the UI, I don't understand why. Can you please explain. I've posted my question here http://stackoverflow.com/questions/37394920/ios-swift-generatecgimagesasynchronouslyfortimes-takes-too-long-and-freezes-th — Sam, May 23 '16 at 19:54

Issue with requesting the video thumbnail using MPMoviePlayer

1 Answers1