SpriteKit Invaders Part 5 - Ending the Game, Showing Extra Lives, and Starting New Rounds

We're nearing the end of this series! In Part 5 we go over the code and pick out spots to cause the game to end. We create functions that start and end the game, set up some animations for when that happens and we take care of displaying any extra lives for the player.
For your own challenge you can work out a score, and an extra live every 1000 points if you like, I couldn't cram it into 15 minutes for this episode.
Part 6 will deal with the AVAudioEngine and wrap it up with some fun sound effects.
The source is on github at: github.com/tcihawaii/spriteki...