A media file used to represent the message in the transcript.
- iOS 10.0+
The media file URL must be a file URL. For video files, the system crops the left and right edges of the media file by 6 points, and rounds its corners. For audio files, it shows a graphical representation of the audio’s waveform.
The template can have either an image or a media file. This property is ignored if the template has a non-
image property. This property defaults to