How to add Subtitle with Video in Apple TV

I am working on Apple TV application. I have one URL of Video and one URL of video Subtitle. I want to play video with subtitle. Anybody have a solution for this problem

If you have please let me know.

There is a Video URL: "https://sample/hls_playlist.m3u8"

There is a Subtitle URL: "https://samplesubtitle=AKIAJS5BLYTDP3J5UOFQ&Expires=1507918258&Signature=r%2FcV7UVSejOBYDKFHwMYtrvXUmM%3D"

This is my code:

func playVideo(_ videoURL: String) {
     let videoAsset = AVURLAsset.init(url: URL(string:videoURL)!) as AVURLAsset
     let mixComposition = AVMutableComposition.init() 

     let videoTrack: AVMutableCompositionTrack? = mixComposition.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: kCMPersistentTrackID_Invalid)
     try? videoTrack?.insertTimeRange(CMTimeRangeMake(kCMTimeZero, videoAsset.duration), of: (videoAsset.tracks(withMediaType: AVMediaTypeVideo)[0]), at: kCMTimeZero)

     let subtitleAsset = AVURLAsset.init(url: URL(string: self.subtitle!)!)
     let subtitleTrack: AVMutableCompositionTrack? = mixComposition.addMutableTrack(withMediaType: AVMediaTypeText, preferredTrackID: kCMPersistentTrackID_Invalid)
     try? subtitleTrack?.insertTimeRange(CMTimeRangeMake(kCMTimeZero, videoAsset.duration), of: subtitleAsset.tracks(withMediaType: AVMediaTypeText)[0], at: kCMTimeZero)

     self.playerItem = AVPlayerItem.init(asset: mixComposition)
     self.playerObj = AVPlayer.init(playerItem: self.playerItem)
     self.playerController?.player = self.playerObj
     self.playerItem.addObserver(self, forKeyPath: Notification.Name.status.rawValue, options: NSKeyValueObservingOptions.new, context: nil)
     self.playerController?.player!.play()
}