I built a custom video player, all buttons are working. I need to know what is the code that does the MPMoviePlayerController display subtitles when the video has that option. I
If your media file has embedded captions MPMoviePlayerViewController will show a button to enable/disable captions. By default, captions are disabled and can not be activated programatically.
Instead, you could use AVPlayer with closedCaptionDisplayEnabled property. But only iOS 4+