跳过下一个跳过上一个Google Cast变灰

Question

与How to add/use GCKMediaQueue in Swift?有关，我在AppDelegate上添加了跳过按钮，它们确实出现在扩展的控制器屏幕上。但是它们变灰了。如果我让视频结束，那么它将播放队列中的下一个。但是，为什么按钮变灰了呢？这通常意味着它们不可用。但是我队列中有50个视频，所以我想念什么？

func addvideos2queue() {
for indexloop in 1 ... 50
       {

        debugPrint("**** Attempting #" + String(indexloop) + " to add another to the que")
            let PTV = playthisvideo() //received random video file name
            let metadata = GCKMediaMetadata()
            metadata.setString("Los Simpsons", forKey: kGCKMetadataKeyTitle)
            metadata.addImage(GCKImage(url: URL(string: self.location + "poster_los_simpson.jpg")!,
                                       width: 480,
                                       height: 360))
            metadata.setString (PTV,
                                forKey: kGCKMetadataKeySubtitle)

            let url = URL.init(string: (self.location + PTV))
            guard let mediaURL = url else {
                print("**** invalid mediaURL")
                return }
            if url == nil {debugPrint("***** URL  was empty")}
            let mediaInfoBuilder = GCKMediaInformationBuilder.init(contentURL: mediaURL)
            mediaInfoBuilder.streamType = GCKMediaStreamType.none;
            mediaInfoBuilder.contentType = "video/mp4"
            mediaInfoBuilder.contentID = String(indexloop)
            mediaInfoBuilder.metadata = metadata;
            let builder = GCKMediaQueueItemBuilder()
            let mediaInformation = mediaInfoBuilder.build()
            builder.mediaInformation = mediaInformation
            builder.autoplay = true
            builder.preloadTime = 15
            let item = builder.build

        if let remoteMediaClient = GCKCastContext.sharedInstance().sessionManager.currentCastSession?.remoteMediaClient {

            if remoteMediaClient.mediaStatus != nil, true {
                let request = remoteMediaClient.queueInsert([item()], beforeItemWithID: kGCKMediaQueueInvalidItemID, customData: kGCKMediaCommandSkipForward)
                request.delegate = self
                debugPrint(" *****  ITS BEEN ADDED ****", request)
                setQueueButtonVisible(true)
            } else {
                let options = GCKMediaQueueLoadOptions()
                options.repeatMode = .all
               options.customData =  kGCKMediaCommandSkipForward
                debugPrint (" ************* First one ", (item()))
                let request = remoteMediaClient.queueLoad([item()], with: options )
                request.delegate = self

            }

        }




}//new end of loop

GCKCastContext.sharedInstance().presentDefaultExpandedMediaControls() // Brings to expaned controller up
}//end of castanthoner