We will begin by building a simple Heads Up Display (HUD) for our game. Its purpose is to show some useful data about the current state of the game to the player. The idea behind making the HUD into a new layer is to simplify the logic of the GameLayer. This way, the GameLayer will only handle stuff of the game itself while leaving the HUD logic to the HUDLayer.
In our game, the HUD will display the remaining lives, score, remaining bombs, and anything you want to display later. Once it is done, all we need to do in the GameLayer is send a message so the HUDLayer gets updated.