audio stream muted after going to speak view and back to listen

[hburgund]

On several occasions while testing, I experienced a state where I could not hear any audio through the app, though I could see that audio was being generated on the server and that the various PATCH and POST requests to the streams/ endpoint were being acted upon on the server.

I can get this to happen by entering the speak view and then going back to listen. There may be other ways to force this odd state, but this one seems to work and is obviously a common use-case.

[hburgund]

It is possible if we move the place where the media player is instantiated to the Listen view per #56, this will be fixed or at least changed as well.

Unfortunately, I have done a lot more testing and the results are inconsistent. Sometimes this muted state happens and other times it does not and I can't figure out what causes the difference. The times when no audio is heard, the "Loading Stream" spinner doesn't appear, which I guess is not surprising.

Sometimes, if I re-select the Exhibition, and then try to play again, it will start playing again, but this too isn't consistent.

We should probably wait until #56 is fixed to see if that has any effect on this and then see if some consistencies can be uncovered.

[seeReadCode]

Does it have to do with:

• whether the player was paused before moving to speak?
• whether a spoken asset was recorded and uploaded?
• whether the contribute flow was canceled?

When the room view disappears this runs:
https://github.com/seeRead/roundware-ios-digita11y/blob/master/Digita11y/RoomsViewController.swift#L292

If you see Map or Text first, the lock on keeping audio playing might not get reset to false before you move to Contribute. So that's a separate bug but related.
https://github.com/seeRead/roundware-ios-digita11y/blob/master/Digita11y/RoomsViewController.swift#L204-L213

Within viewAppear, we could a check for that lock, if it's true, reset it to false, else run startPlaying()

https://github.com/seeRead/roundware-ios-digita11y/blob/master/Digita11y/RoomsViewController.swift#L301