Returns the beat that will be (or was) played at the specified host time.
- iOS 9.0+
- macOS 10.11+
- Mac Catalyst 13.0+
- tvOS 9.0+
This call is only valid if the player is playing and will return
0 with an error if the player is not playing or if the starting time of the player was after the specified host time. This method uses the sequence's tempo map to retrieve a beat time from the starting and specified host time.