Document textTracks support for iOS

--- | ---

title | Descriptive name for the track

language | 2 letter [ISO 639-1 code](https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes) representing the language

type | Mime type of the track<br> * TextTrackType.SRT - .srt SubRip Subtitle<br> * TextTrackType.TTML - .ttml TTML<br> * TextTrackType.VTT - .vtt WebVTT

type | Mime type of the track<br> * TextTrackType.SRT - SubRip (.srt)<br> * TextTrackType.TTML - TTML (.ttml)<br> * TextTrackType.VTT - WebVTT (.vtt)<br>Android supports all 3 types, iOS only supports VTT

uri | URL for the text track. Currently, only tracks hosted on a webserver are supported

Example:

  {

    title: "English CC",

    language: "en",

    type: "text/vtt", TextTrackType.VTT,

    type: TextTrackType.VTT, // "text/vtt"

    uri: "https://bitdash-a.akamaihd.net/content/sintel/subtitles/subtitles_en.vtt"

  },

  {

    title: "Spanish Subtitles",

    language: "es",

    type: "application/x-subrip", TextTrackType.SRT,

    type: TextTrackType.SRT, // "application/x-subrip"

    uri: "https://durian.blender.org/wp-content/content/subtitles/sintel_es.srt"

  }

]}

```

This isn't support on iOS because AVPlayer doesn't support it. Text tracks must be loaded as part of an HLS playlist.

On iOS, sidecar text tracks are not supported for HLS playlists. For HLS playlists, you should include the text tracks as part of the playlist.

Platforms: Android ExoPlayer

Platforms: Android ExoPlayer, iOS

#### useTextureView

Output to a TextureView instead of the default SurfaceView. In general, you will want to use SurfaceView because it is more efficient and provides better performance. However, SurfaceViews has two limitations: