Creating the health power-up crate

We have taken many steps to create our crate system. Now we can add our first crate: a crate in the GameScene class that will award health points to the player. Follow these steps to wire up the heart crate:

1. In GameScene.swift, instantiate a new instance of the Crate class as a property of GameScene:

           let heartCrate = Crate() 

2. At the bottom of the GameScene didMove function, add the heartCrate to the node tree and call the function that makes it award a heart:

           // Spawn the heart crate, out of the way for now 
           self.addChild(heartCrate) 
           heartCrate.position = CGPoint(x: -2100, y: -2100) 
           heartCrate.turnToHeartCrate() 

3. Locate the GameScene.didSimulatePhysics function. Find the code that spawns the power-up star. We can add on to this code to spawn our heart crate randomly after some encounters. Add the following code below the starRoll conditional (new code in bold):

           // Each encounter has a 10% chance to spawn a star...