XCDYouTubeClient Not playing Video in Swift 4

I am trying to play youtube videos by XCDYouTubeClient library but it not play the video.I also refer the documentation but it didn't help me to resolve issue

let playerViewController = AVPlayerViewController()self.present(playerViewController, animated: true, completion: nil)XCDYouTubeClient.default().getVideoWithIdentifier("tG7vx7-3sl0") { [weak playerViewController] (video: XCDYouTubeVideo?, error: Error?) in      if let streamURLs = video?.streamURLs, let streamURL = (streamURLs[XCDYouTubeVideoQualityHTTPLiveStreaming] ?? streamURLs[XCDYouTubeVideoQuality.HD720] ?? streamURLs[XCDYouTubeVideoQuality.medium360] ?? streamURLs[XCDYouTubeVideoQuality.small240]) {           playerViewController?.player = AVPlayer(url: streamURL)      } else {           self.dismiss(animated: true, completion: nil)       }}

Thanks